A pro-Russian activist aims a pistol at supporters of the Kiev government during clashes in the streets of Odessa May 2, 2014. Police said a man was shot dead in clashes between a crowd backing Kiev and pro-Russian activists in the largely Russian-speaking southern port of Odessa, which lies west of Crimea, annexed by Moscow in March. (Photo by Yevgeny Volokin/Reuters)

A pro-Russian activist runs during clashes with supporters of the Kiev government in the streets of Odessa May 2, 2014. (Photo by Yevgeny Volokin/Reuters)

Pro-Russian activists hurl objects at supporters of the Kiev government in the streets of Odessa May 2, 2014. (Photo by Yevgeny Volokin/Reuters)

Armed pro-Russian activists look on during clashes with supporters of the Kiev government in the streets of Odessa May 2, 2014. (Photo by Yevgeny Volokin/Reuters)

An injured pro-Russian activist looks on during clashes with supporters of the Kiev government in the streets of Odessa May 2, 2014. (Photo by Yevgeny Volokin/Reuters)

A pro-Russian activist hurls an object at supporters of the Kiev government during calshes in the streets of Odessa May 2, 2014. (Photo by Yevgeny Volokin/Reuters)

People pull up cobblestones as ammunition during clashes between pro-Russian activists and supporters of the Kiev government in the streets of Odessa May 2, 2014. Police said a man was shot dead in clashes between a crowd backing Kiev and pro-Russian activists in the largely Russian-speaking southern port of Odessa, which lies west of Crimea, annexed by Moscow in March. (Photo by Yevgeny Volokin/Reuters)

Ukrainian police help an injured colleague during clashes between pro-Russian activists and supporters of the Kiev government in the streets of Odessa May 2, 2014. (Photo by Yevgeny Volokin/Reuters)

Police take cover as pro-Russian activists and supporters of the Kiev government clash in the streets of Odessa May 2, 2014. (Photo by Yevgeny Volokin/Reuters)

A pro-Russian activist hurls an object at supporters of the Kiev government during clashes in the streets of Odessa May 2, 2014. (Photo by Yevgeny Volokin/Reuters)

A Ukrainian government supporter holds a stone and a stick during a clash with pro-Russians in the Black Sea port of Odessa, Ukraine, Friday, May 2, 2014. A clash broke out late Friday between pro-Russians and government supporters in Odessa, on the Black Sea coast some 550 kilometers (330 miles) from the turmoil in the east. Odessa had remained largely untroubled by unrest since the February toppling of pro-Russia President Viktor Yanukovych, which ignited tensions in the east. (Photo by Sergei Poliakov/AP Photo)

Pro-Russian activists hurl objects at supporters of the Kiev government during clashes in the streets of Odessa May 2, 2014. (Photo by Yevgeny Volokin/Reuters)

Protesters look at a fire in the trade union building in Odessa May 2, 2014. (Photo by Yevgeny Volokin/Reuters)

People wait to be rescued on upper storeys at the trade union building in Odessa May 2, 2014. (Photo by Yevgeny Volokin/Reuters)

People wait to be rescued on the ledge of the second floor during a fire at the trade union building in Odessa May 2, 2014. (Photo by Yevgeny Volokin/Reuters)

People wait to be rescued on an upper storey ledge during a fire at the trade union building in Odessa May 2, 2014. (Photo by Yevgeny Volokin/Reuters)

People wait to be rescued on the second storey's ledge during a fire at the trade union building in Odessa May 2, 2014. (Photo by Yevgeny Volokin/Reuters)

A protester throws a petrol bomb at the trade union building in Odessa May 2, 2014. (Photo by Yevgeny Volokin/Reuters)

People wait for rescue on an upper storey ledge during a fire at the trade union building in Odessa May 2, 2014. At least 38 people were killed in a fire on Friday in the trade union building in the centre of Ukraine's southern port city of Odessa, regional police said. (Photo by Yevgeny Volokin/Reuters)

A protester walks past a burning pro-Russian tent camp near the trade union building in Odessa May 2, 2014. (Photo by Yevgeny Volokin/Reuters)

A protester walks past a burning pro-Russian tent camp near the trade union building in Odessa May 2, 2014. (Photo by Yevgeny Volokin/Reuters)

Ukrainian soldiers take position at a checkpoint they seized in the early morning in the village of Andreevka, 7 kms from the centre of the southern Ukrainian city of Slavyansk, on May 2, 2014. Ukraine's military lost two helicopters and two servicemen on May 2 in a deadly offensive launched just before dawn against pro-Russian rebels holding the flashpoint town of Slavyansk, insurgents and authorities said. (Photo by Vasily Maximov/AFP Photo)

A pro-Russian separatist stands guard near an armoured personnel carrier in the town of Slaviansk in eastern Ukraine May 2, 2014. (Photo by Baz Ratner/Reuters)

Ukrainian soldiers stay near of a checkpoint seized by them not far of Slaviansk, Ukraine, 02 May 2014. At least three people were killed and several were injured in clashes between Ukrainian forces and pro-Russian separatists in the eastern city of Sloviansk early on 02 May. The Ukraininan Defence Ministry said that two crew members were killed and an unspecified number of soldiers were injured after separatists shot down two Mi-24 assault helicopters with surface-to-air missiles. A third, Mi-8 transport helicopter, was hit by bullets but escaped unharmed, the ministry said. “Putin has called such an operation a criminal action. Sadly the latest developments fully support that”, says Russian President Vladimir Putin's spokesman, and has practically destroyed the last hope for a diplomatic solution to the crisis. (Photo by Roman Pilipey/EPA)

A handout picture released be the Ukrainain Defence Ministry Press Service on 02 May 2014 claims to show several weapons, mobile phones and other items, all allegedly belonging to four people suspected of having shot down a Ukrainian helicopter, being presented next to the four people arrested by Ukrainian forces near of a checkpoint near Slaviansk, Ukraine, 02 May 2014. At least three people were killed and several were injured in clashes between Ukrainian forces and separatists in the eastern city of Sloviansk early on 02 May. The Ukrainian Defence Ministry said that two crew members were killed and an unspecified number of soldiers were injured after separatists shot down two Mi-24 assault helicopters with surface-to-air missiles. Sloviansk has been at the centre of a separatist uprising in eastern Ukraine. The city of some 100,000 has been held by well-armed militias for weeks. (Photo by EPA/Ukrainian Defence Ministry Press)

A woman stands with an Orthodox icon at a Ukrainian checkpoint near the town of Slaviansk in eastern Ukraine May 2, 2014. (Photo by Baz Ratner/Reuters)

A Ukrainian military helicopter flies near a Ukrainian checkpoint near the town of Slaviansk in eastern Ukraine May 2, 2014. (Photo by Baz Ratner/Reuters)

Ukrainian troops guard a checkpoint near the town of Slaviansk in eastern Ukraine May 2, 2014. (Photo by Baz Ratner/Reuters)

Ukrainian soldiers look on at a Ukrainian checkpoint near the eastern town of Slaviansk May 2, 2014. (Photo by Baz Ratner/Reuters)

Ukrainian soldiers sit on a armoured personnel carrier at a Ukrainian checkpoint near the eastern town of Slaviansk May 2, 2014. (Photo by Baz Ratner/Reuters)

Ukrainian Army soldiers are seen atop of a bridge while Pro Russia civilians block the road in the village of Andreevka, 10 km south of Slavyansk, Ukraine, Friday, May 2, 2014. Russia has massed tens of thousands of troops in areas near Ukraine’s border. Kiev officials claim Russia is preparing to invade and that it is fomenting the unrest in the east, where insurgents have seized government buildings in about a dozen cities in towns. Moscow denies the allegations, but Foreign Minister Sergey Lavrov has warned Russia would respond to attacks on Russian citizens or interests in the east. (Photo by Manu Brabo/AP Photo)

A pro-Russian separatist guards a checkpoint as tyres burn behind him near the town of Slaviansk in eastern Ukraine May 2, 2014. Ukraine launched a “large-scale operation” to retake the eastern town of Slaviansk, pro-Russian separatists there said on Friday, in an escalation of violence in what has become the worst confrontation between Russia and the West since the Cold War. (Photo by Baz Ratner/Reuters)

Ukrainian Army soldiers line up in front of Pro Russia civilians who where blocking the road in the Andreevka, 10 km south to Slaviansk, Ukraine, Friday, May 2, 2014. (Photo by Manu Brabo/AP Photo)

Pro-Russian separatists guard a checkpoint near the town of Slaviansk in eastern Ukraine May 2, 2014. (Photo by Baz Ratner/Reuters)

A pro-Russian separatist guards a checkpoint as tyres burn in front of him, near the town of Slaviansk in eastern Ukraine May 2, 2014. (Photo by Baz Ratner/Reuters)

A pro-Russian separatist stands guard on top of an armoured personnel carrier in the town of Slaviansk in eastern Ukraine May 2, 2014. (Photo by Baz Ratner/Reuters)

A Ukrainian military helicopter lands near a Ukrainian checkpoint near the town of Slaviansk in eastern Ukraine May 2, 2014. Ukrainian forces attacked the rebel-held city of Slaviansk before dawn on Friday and pro-Russia separatists shot down at least one attack helicopter, killing a pilot, in a sharp escalation of the conflict. (Photo by Baz Ratner/Reuters)

A Ukrainian soldier stands guard on the railway tracks near the town of Slaviansk in eastern Ukraine May 2, 2014. (Photo by Baz Ratner/Reuters)

Ukrainian soldiers sit on an armoured personnel carrier at a Ukrainian checkpoint near the eastern town of Slaviansk May 2, 2014. (Photo by Baz Ratner/Reuters)

Ukrainian soldiers stand guard at a Ukrainian checkpoint near the eastern town of Slaviansk May 2, 2014. (Photo by Baz Ratner/Reuters)

Ukrainian soldiers stand guard at a Ukrainian checkpoint near the eastern town of Slaviansk May 2, 2014. (Photo by Baz Ratner/Reuters)

A boy with a toy gun walks in front of seized regional government headquarters in Luhansk, eastern Ukraine, May 2, 2014. Ukrainian forces attacked the rebel-held city of Slaviansk before dawn on Friday and pro-Russia separatists shot down at least one attack helicopter, killing a pilot, in a sharp escalation of the conflict. (Photo by Vasily Fedosenko/Reuters)