With their operatives on the run, the Palestinian militant groups Hamas and Islamic Jihad have increasingly forged a common front against Israel, and there are signs they are also being guided by Lebanese Hezbollah (searchguerrillas.

Days after ishoming a joint statement calling for coordinated "resistance" against Israel, the two groups attacked an Israeli army base Friday in the Netzarim settlement in the Gaza Strip (search), killing three soldiers and reviving heated debate in Israel over whether to hang on to the Jewish enclave.

The two groups have cooperated to a lesser degree in the past, with militants joining forces at the local level, but last week's call for coordinated attacks signals closer ties -- a consolidation that might make the groups more efficient and more difficult to bring down.

Adnan Asfour, a Hamas (search) leader in the West Bank, said the alliance with Islamic Jihad is a response to Israel's increasing military pressure, including its hunt for members of the groups' military wings and, more recently, political leaders.

"With the expansion of Israel's circle of aggression, there must be an expansion of the circle of resistance," said Asfour, adding that other militant groups may be invited into an alliance.

Israeli officials are clearly concerned, especially by what some say is a growing involvement of Hezbollah, a militant group backed by Syria and Iran. Defense Minister Shaul Mofaz and the army chief, Lt. Gen. Moshe Yaalon, told the Cabinet on Sunday that Islamic Jihad (searchand Hezbollah are planning joint attacks in Israel.

Hezbollah spearheaded a successful campaign to end Israel's 18-year occupation of southern Lebanon in 2000, and can offer Palestinian groups a wealth of knowledge about everything from military training to arms smuggling.

An earlier generation of Hamas activists is believed to have learned from Hezbollah when several hundred of them, in the wake of a Hamas killing of an Israeli soldier, were deported to Lebanon a decade ago, staying for about a year.

"Cooperation with Hezbollah strengthens the Islamic Jihad and Hamas," said Boaz Ganor, an Israeli counterterrorism expert.

Since Israeli-Palestinian fighting erupted three years ago, Hamas and Islamic Jihad have carried out 15 joint operations, mostly gun battles, according to Hamas.

The deadliest, a joint strike June 8 that also included the Al Aqsa Martyrs' Brigade, a militant group with ties to Yasser Arafat's Fatah movement, killed four soldiers before the gunmen were shot dead.

The two groups' leaders convened a meeting Oct. 20 chaired by Khaled Mashaal, head of Hamas' political bureau, and Ramadan Abdullah Shallah, leader of Islamic Jihad.

A statement faxed that day to The Associated Press in Beirut said "the two movements agreed to confront the Zionist aggression on our people in Palestine and to urge all (Palestinian) factions and resistance forces to coordinate among each other to confront this aggression."

The statement was widely interpreted by group members and observers as heralding an alliance in which the groups would more often coordinate their actions.

But the close ties may not last. Even though Hamas and Islamic Jihad share a fundamentalist Islamic ideology, they have long been rivals and past efforts at cooperation have broken down.

Hamas is a large group with popular support, especially in the Gaza Strip, and includes a political wing that focuses on charity and welfare programs. The smaller Islamic Jihad, which has backing from Iran, sticks to violent activities. Other Palestinian factions are largely secular.

The Hamas-Islamic Jihad alliance has been in the works for some time, said Moheb Nawatie, a Palestinian expert on Islamic movements.

As the U.S. war on terror has progressed, Hamas and Islamic Jihad have found themselves under heavy international pressure, with the United States and the European Union declaring them terror groups and freezing funds.

"They feel that Israel and the entire the world are pushing them into a corner, and in this corner they can find people who are facing the same thing, like Iran and Hezbollah," Nawatie said.

The extent of Hezbollah's involvement in the Palestinian territories remains murky. Nawatie said he detects increasing cooperation between Palestinian groups and Hezbollah, though not yet on the "military" level.

Osama Hamdan, a Hamas leader in Lebanon, said Hezbollah had not been actively involved in attacks against Israel and the group was not present at the Oct. 20 meeting.

Asfour said Hamas leaders later met separately with Hezbollah representatives "for the purpose of political and public relations cooperation."

Still, Friday's attack in Netzarim was the latest of a series of Palestinian attacks with Hezbollah's fingerprints.

Hamas and Islamic Jihad spent weeks spying on Netzarim, planning the attack and waiting for ideal weather conditions -- a pea-soup fog -- to move in. Two gunmen -- one of whom escaped -- burst into the soldiers' sleeping quarters, spraying machine-gun fire in all directions.

Hours later, the groups released a videotape showing Hamas gunman Samir Fouda, 21, who was killed, standing alongside his surviving Islamic Jihad compatriot, whose face was blurred to protect his identity.

Surveillance footage of the settlement -- showing settler's cars and bike riders moving along the town's roads -- is reminiscent of images Hezbollah would release after successful attacks on the Israeli army.

Another attack in the Gaza Strip on Oct. 15, in which a remote-controlled bomb was detonated under a U.S. diplomatic convoy, killing three Americans, was similar to attacks carried out by Hezbollah in Lebanon, experts said.

Ganor, the counterterrorism expert, said Hezbollah's attacks on Israeli soldiers in Lebanon eventually turned the Israeli public against the occupation of Lebanon and forced an Israeli pullback.

Now Hezbollah is teaching Hamas and Islamic Jihad. "It's the same model as we saw in Lebanon time after time," he said.