An Israeli army officer gives explanations to journalists during an army organised tour in a tunnel said to be used by Palestinian militants for cross-border attacks, July 25, 2014. (Photo by Jack Guez/Reuters)

An Israeli army officer walks during an army organised tour for journalists in a tunnel said to be used by Palestinian militants for cross-border attacks, July 25, 2014. (Photo by Jack Guez/Reuters)

An Israeli army officer stands at the entrance of a tunnel said to be used by Palestinian militants for cross-border attacks, during an army organised tour for journalists on July 25, 2014. (Photo by Jack Guez/Reuters)

A Palestinian smuggler climbs down into a tunnel, temporarily closed by Hamas forces, beneath the Egyptian-Gaza border in Rafah in the southern Gaza Strip April 14, 2010. (Photo by Ibraheem Abu Mustafa/Reuters)

A Palestinian smuggler rests near the entrance to a tunnel beneath the Egyptian-Gaza border in Rafah in the southern Gaza Strip August 12, 2010. While Israeli air strikes and Egyptian bombs hurt the once-flourishing trade, they failed to close it down. But Israel's decision to let imports flow more freely to Gaza has put many tunnels out of business and many workers out of a job. (Photo by Ibraheem Abu Mustafa/Reuters)

A Palestinian smuggler holds up fish smuggled through a tunnel beneath the Egypt-Gaza border in Rafah in the southern Gaza Strip February 21, 2010. With their fishermen at risk of being shot at by the Israeli navy, Palestinians in the Gaza Strip are finding new ways to supply the blockaded territory with a staple that is in short supply. (Photo by Ibraheem Abu Mustafa/Reuters)

A Palestinian smuggler hauls a calf out from a tunnel that goes beneath the Egyptian-Gaza border October 24, 2008. Hundreds of Gaza merchants throng around the border area of Rafah every day to pick up merchandise coming to Gaza from Egypt via subterranean passages that have created a flourishing trade zone. (Photo by Mohammed Salem/Reuters)

Egyptian soldiers stand guard outside smuggling tunnels beneath the Egyptian-Gaza border in Rafah, in the southern Gaza Strip February 19, 2013. (Photo by Ibraheem Abu Mustafa/Reuters)

A masked Palestinian surveys a destroyed smuggling tunnel near the Gaza-Egypt border in the southern Gaza Strip January 28, 2009. (Photo by Ibraheem Abu Mustafa/Reuters)

A Palestinian worker repairs a smuggling tunnel flooded by Egyptian forces, beneath the Egyptian-Gaza border in Rafah, in the southern Gaza Strip February 10, 2013. Egyptian forces have flooded smuggling tunnels under the border with the Palestinian-ruled Gaza Strip in a campaign to shut them down, Egyptian and Palestinian officials said. (Photo by Ibraheem Abu Mustafa/Reuters)

A man walks near a tunnel linking Egypt and the Gaza Strip, at Rafah city, about 350 km (217 miles) northeast of Cairo August 9, 2012. (Photo by Mohamed Abd El Ghany/Reuters)

Palestinians smoke cigarettes as they work inside a smuggling tunnel dug beneath the Egyptian-Gaza border in Rafah, in the southern Gaza Strip November 26, 2012. Knee-deep in craters carved out by Israeli air strikes, Palestinians wielded shovels and planks to reopen tunnels used to smuggle in goods from Egypt to Gaza, as international aid agencies raced to replenish Gaza's supplies. (Photo by Mohammed Salem/Reuters)

The starting tip of an active tunnel that supplies Gaza with gravel for construction is pictured in Rafah city September 12, 2012. Tonnes of gravel were supplied to Gaza through this tunnel. Tunnel work between Egypt's border city of Rafah and Gaza has gone uninterrupted despite the army's security campaign. (Photo by Asmaa Waguih/Reuters)

A Palestinian man calls on smugglers as he brings gravel into a smuggling tunnel beneath the Gaza-Egypt border in Rafah in the southern Gaza Strip June 24, 2013. (Photo by Ibraheem Abu Mustafa/Reuters)

Palestinians smuggle cement outside a tunnel beneath the Egyptian-Gaza border in Rafah, in the southern Gaza Strip September 17, 2012. (Photo by Ibraheem Abu Mustafa/Reuters)

A Palestinian looks up while repairing a smuggling tunnel in Rafah near Gaza's border with Egypt January 22, 2009. (Photo by Ibraheem Abu Mustafa/Reuters)

A Palestinian tunnel worker uses his mobile as he rests inside a smuggling tunnel beneath the Gaza-Egypt border in the southern Gaza Strip July 19, 2013. (Photo by Ibraheem Abu Mustafa/Reuters)

A Palestinian smuggler speaks on a phone with other smugglers in a tunnel beneath the Egyptian-Gaza border October 21, 2008. Hundreds of Gaza merchants throng around the border area of Rafah every day to pick up merchandise coming to Gaza from Egypt via subterranean passages that have created a flourishing trade zone. (Photo by Suhaib Salem/Reuters)

A Palestinian smuggler pushes a calf through a tunnel beneath the Egyptian-Gaza border October 24, 2008. (Photo by Mohammed Salem/Reuters)

Palestinian tunnel workers smoke cigarettes as they rest inside a smuggling tunnel flooded by Egyptian security forces, beneath the Gaza-Egypt border in the southern Gaza Strip September 10, 2013. (Photo by Ibraheem Abu Mustafa/Reuters)

A Palestinian tunnel worker gestures as he repairs a smuggling tunnel flooded by Egyptian security forces, beneath the Gaza-Egypt border in the southern Gaza Strip September 10, 2013. (Photo by Ibraheem Abu Mustafa/Reuters)

A Palestinian tunnel worker is lowered on a rope into a smuggling tunnel dug beneath the Gaza-Egypt border in the southern Gaza Strip August 26, 2013. (Photo by Mohammed Salem/Reuters)

A Palestinian security officer prepares to seal a tunnel used to smuggle arms during an operation next to the border with Egypt at the Rafah refugee camp in the southern Gaza Strip December11, 2005. (Photo by Mohammed Salem/Reuters)