An Egyptian security official declared the blockade of Gaza a failure Monday and said his country will keep its border with the Palestinian territory open indefinitely.

Keeping that crossing point open long term would ease the blockade imposed by Israel three years ago to isolate and punish Gaza's Hamas rulers. It also restores a link to the outside the world for some of Gaza's 1.5 million Palestinians.

Obama Administration Biden: US seeks new ways to deal with Gaza AFP American vice president meets with Egyptian President Mubarak in Sharm el-Sheikh, says discussed ways to address humanitarian, economic, security and political situation in Strip Biden: US seeks new ways to deal with Gaza

Egypt opened its border with Gaza 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.

In another escalation of the tension off Gaza's shores, Israeli naval forces shot and killed four men wearing wet suits off the coast on Monday, and the militant group Al-Aqsa Martyrs' Brigades said they were members of its marine unit training for a mission.

Vice President Joe Biden said Monday 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." He issued the statement after meeting Egyptian President Hosni Mubarak in the Egyptian Red Sea resort of Sharm El-Sheikh.

Egypt and Israel have maintained the blockade since Hamas took control of Gaza in 2007, with Israel describing it as an essential measure to stop weapons from reaching Hamas militants, who have hit southern Israel with rockets and in past years killed hundreds in suicide bombings.

The Egyptian security official said, however, that the closure has failed to achieve its goals, including the release of an Israeli soldier held by Hamas since 2006. Israeli airstrikes and Egyptian security efforts have also yet to choke off a bustling smuggling trade that uses hundreds of tunnels along the Gaza-Egypt border, though the official said Egypt is determined to shut them down.

The crossing point at the border town of Rafah is still subject to restrictions, with Egypt letting in some humanitarian aid and allowing Palestinians into Egypt on a case-by-case basis for medical treatment or to travel onward to attend foreign universities, for example.

'Hamas becomes more extremist'

Egypt will not allow in large cargo shipments or construction material because the terminal is designed primarily as a crossing for travelers, said the official, who spoke on condition of anonymity because of the sensitivity of the issue.

For its part, Israel allows through only basic humanitarian goods, blocking crucial items like cement needed to rebuild war damage because it argues the material could be used by Hamas. The closure has crushed Gaza's already fragile economy.

The Egyptian official said Israel must work out a new policy to end the suffering of the Palestinians while keeping pressure on Hamas.

Like Israel, Egypt also fears sharing a border with a slice of territory controlled by Islamic militants backed by regional rival Iran. Concerned about the flow of weapons, Egypt late last year began building an underground, metal barrier to seal the smuggling tunnels.

"We have a constant security concern, because Iran has its aims, Hezbollah has its aims, Hamas has its aspirations and aims, and al-Qaeda can very well be present in Sinai and Gaza," the official said.

Egypt has been harshly criticized in the Muslim world for having helped maintain the blockade.

The official called it a "continuously embarrassing situation" for Egypt and blamed Israel for thinking the closure could pressure Hamas to release the captured soldier, Gilad Shalit.

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

In Monday's clash, the Israeli military said a naval force spotted the Palestinians in the waters off Gaza and opened fire. It claimed the forces had prevented an attack on Israeli targets.

Al-Aqsa Martyrs' Brigades said the four killed were training in Gaza's waters. The violent offshoot of Palestinian President Mahmoud Abbas' Fatah faction, made the claim in a text message sent to reporters in Gaza.

Four bodies were retrieved and taken to a hospital in central Gaza, said Moawiya Hassanain, a Palestinian health official. The Palestinian naval police said two people were still missing.

"The bloody escalation today is a desperate attempt by the occupation government to divert the world attention away from the massacre committed against the flotilla," Hamas spokesman Sami Abu Zuhri told reporters in Gaza.

The May 31 flotilla clash, in which eight Turkish men and one dual American-Turkish citizen were killed aboard one of the vessels seized by Israeli commandos, has put Israel under international pressure to lift or at least ease the blockade.

The killings seriously damaged Israel's relations with Turkey, which had been its closest ally in the Muslim world. In Istanbul, a 20-member Asian security group kicked off a summit with Turkey seeking to condemn Israel for the raid.

Israel has sought to portray the nine activists killed as terrorsits, saying they prepared for the fight before boarding the flotilla. The military Monday released the names of five of the activists it said have long-standing ties to terror organizations.

"The state of Israel is under attack," Prime Minister Benjamin Netanyahu told lawmakers in his Likud party. He said the attack was a "direct continuation" of international condemnations of Israel's war against Hezbollah guerrillas in 2006 and last year's military offensive against Hamas in Gaza.