Egyptian and Palestinian officials say that Egyptian forces have flooded smuggling tunnels under the border with the Palestinian-ruled Gaza Strip in a campaign to shut them down.  These tunnels are considered to be a vital lifeline for Gaza, bringing in an estimated 30 percent of all goods that reach the enclave and circumventing a blockade imposed by Israel for more than seven years.

Reports from Reuters claimed that they saw one tunnel that was used for bringing in cement and gravel, was suddenly filled with water that sent the workers rushing for safety on Sunday. Locals have witnessed two other tunnels being flooded by Egyptians who were constantly pumping in water.

Abu Ghassan, who supervises the work of 30 men at one tunnel some 200 meters (yards) from the border fence, has said that the Egyptians have intentionally opened the water to drown the tunnels.

An Egyptian security official in the Sinai told Reuters the campaign started five days ago. “We are using water to close the tunnels by raising water from one of the wells,” he said, declining to be named.

Dozens of tunnels had been destroyed since last August following the killing of 16 Egyptian soldiers in a militant attack near the Gaza fence.

Cairo said some of the gunmen had crossed into Egypt via the tunnels - a charge denied by Palestinians - and ordered an immediate crackdown.

The move surprised and angered Gaza’s rulers, the Islamist group Hamas, which had hoped for much better ties with Cairo following the election last year of Egyptian President Mohamed Mursi, an Islamist who is ideologically close to Hamas.

A Hamas official confirmed Egypt was targeting the tunnels again. He didn’t provide further details and declined to speculate on the timing of the move, which started while Palestinian faction leaders met in Cairo to try to overcome deep divisions.

Hamas said on Monday the Egyptian-brokered talks, aimed at forging a unity government and healing the schism between politicians in Gaza and the occupied West Bank, had gone badly but had not collapsed.

While Gaza’s rulers have been reluctant to criticize Mursi in public, ordinary Gazans are slightly more vocal.

“Egyptian measures against tunnels have worsened since the election of Mursi. Our Hamas brothers thought he would open up Gaza. I guess they were wrong,” said a tunnel owner, who identified himself only as Ayed, fearing reprisal.

“Perhaps 150 or 200 tunnels have been shut since the Sinai attack. This is the Mursi era,” he added.

The tunnellers fear the water being pumped underground might collapse the passage ways, with possible disastrous consequences.

“Water can cause cracks in the wall and may cause the collapse of the tunnel. It may kill people,” said Ahmed Al-Shaer, a tunnel worker whose cousin died a year ago when a tunnel caved in on him.

Six Palestinians have died in January in tunnel implosions, raising the death toll amongst workers to 233 since 2007, according to Gazan human rights groups, including an estimated 20 who died in various Israeli air attacks on the border lands.

Israel imposed its blockade for security reasons back in 2007. The United Nations has appealed for the barrier to be lifted.

At one stage an estimated 2,500-3,000 tunnels have snuck their way under the desert fence but the network has shrunk markedly since 2010, when Israel eased some of the limits they imposed on imports into the coastal enclave.

All goods still require screening before entering Gaza and Israel says some restrictions must remain on items that could be used to make or to store weapons.

This ensures the tunnels are still active, particularly to bring in building materials. Hamas also prefers using the tunnels to smuggle in fuel, thereby avoiding custom dues that are payable on oil crossing via Israel.