After three years of co-operating in the Israeli blockade of Gaza, Egypt said that it will leave its border with the Palestinian territory open indefinitely for humanitarian aid and restricted travel.

With international pressure building to ease the blockade, an Egyptian security official said on Monday that sealing off Hamas-ruled Gaza has only bred more militancy.

The decision to ease the restrictions erected by Israel to isolate and punish Hamas comes a week after a deadly Israeli raid on a flotilla bound for Gaza. The move restores a link to the outside world for at least some of Gaza’s 1.5 million Palestinians.

It also appeared to defuse anger in the Arab and Muslim world over Egypt’s role in maintaining the blockade and to show that Egypt, too, is now pressing Israel to open at least its land crossings with Gaza.

“Egypt is the one that broke the blockade,” said Egyptian foreign ministry spokesman Hossam Zaki. “We are not going to let the occupying power escape from its responsibilities.”

The US, which has called the current border restrictions unsustainable, is among those pressing for changes. The US vice president Joe Biden met with the Egyptian president Hosni Mubarak in the Red Sea resort of Sharm El-Sheikh on Monday.

He released a statement afterward saying the US is closely consulting with Egypt and other allies to find new ways to “address the humanitarian, economic, security, and political aspects of the situation in Gaza.”

For the time being, Egypt is only allowing a restricted group of Gazans to leave the territory, including medical patients, students attending foreign universities and those with residency abroad.

In nearly a week, thousands of Gazans have left and 500 tons of medical supplies were trucked in. It has done so before, sporadically and for a period limited to two or three days.

Egypt will not transfer large cargo shipments or construction material because the border crossing is designed primarily for travellers, a security official said.

Egypt was not exactly a reluctant participant in imposing the blockade. Like Israel, Egypt watched with concern as Hamas militants wrenched control of Gaza from their rivals in the Fatah movement of Western-backed president Mahmoud Abbas during bloody street battles in 2007.

Egypt fears sharing a border with a territory controlled by militants who have the backing of rising regional rival Iran. Just to the south, Egypt’s Sinai peninsula has been the scene of major terrorist attacks against tourist hotels, the last one in 2006.

In announcing the change in Egypt’s position, a security official acknowledged his country was in a “continuously critical situation,” and he said Israel was wrong to think the closure could pressure Hamas to meet a series of demands, including the release of an Israeli soldier, Gilad Schalit, who has held since 2006.

“Israel still insists that the blockade is a pressure tool. It can release Schalit and force Hamas to stop resistance. ... On the contrary, it becomes more extremist,” said the official.

And while it eases movement at the crossing in the border town of Rafah, Egypt is intensifying its efforts to stop a thriving smuggling trade through hundreds of tunnels under the border. Those passages have been Gaza’s key economic lifeline but have also been a pathway for weapons.

Late last year, Egypt began building an underground, metal barrier to seal the smuggling tunnels. The work is expected to be finished in the next few months.

“We have a constant security concern, because Iran has its aims. Hizbollah has its aims. Hamas has its aspirations and aims, and al Qa'eda could very well be present in Sinai and Gaza,” the official said.

Egypt’s decision to open the border came soon after Israel’s deadly raid on an international flotilla of activists trying to break the blockade a week ago. Israel has not publicly protested the Egyptian move, but officials declined to comment Monday.

Iran’s Red Crescent Society said yesterday that it was preparing to send three cargo ships and a plane with humanitarian supplies for Gaza in cooperation with Turkey, whose government unofficially sponsored last week’s attempt to break the blockade.

It was not clear if the ships would actually attempt to sail from Iran, in which case Egypt would most likely stop them at the Suez Canal. The Egyptian security official said he feared an Iranian ship heading to Gaza would only complicate efforts to ease the blockade.

In any event, Israel said it would not allow the vessels to dock in Gaza.

Israeli military officials said their navy is ready for all scenarios. They said if armed Iranian forces tried to enter Gaza, they would be repelled by force.

Hamas welcomed the Egyptian border measures but said it hoped all Gazans would soon be able to travel freely without restrictions. Hamas tightly controls access to Rafah, and only travellers with the proper permits can reach the terminal.

The Israeli prime minister Benjamin Netanyahu has signalled in recent days that he is open to easing the blockade, but cannot allow ships to sail freely into Gaza’s port, fearing weapons will reach Hamas militants.