JERUSALEM - The militant Islamic Jihad group in Gaza fired more than a dozen rockets at southern Israel early Thursday after Israeli undercover forces killed one of its West Bank leaders. The attacks shattered a recent lull in Gaza fighting and highlighted the fragility of efforts to move Israel and Gaza's Islamic Hamas rulers toward an informal truce.

The Islamic Jihad commander, Mohammed Shehadeh, and three other gunmen killed in the previous day's raid were buried in the West Bank town of Bethlehem on Thursday. The bodies of Shehadeh and another militant were wrapped in flags of the Lebanese Hezbollah guerrilla group, and dozens of mourners chanted, "Hezbollah is coming" - a sign of the Iranian-backed militia's growing influence on Palestinian militants.

A dozen rockets and three mortars were fired at Israel late Wednesday and early Thursday, Israeli security officials said. Two rockets struck a warehouse and soccer stadium in the rocket-weary Israeli town of Sderot, but no one was injured. Israeli aircraft struck a loaded rocket launcher early Thursday, but no Palestinian injuries were reported.

The rocket barrage from Gaza was practically a given after Israeli undercover forces opened fire on the car carrying Shehadeh. The Israeli military said the Islamic Jihad commander planned suicide bombings that killed dozens of Israelis.

Israeli Defense Minister Ehud Barak said Israel would keep pursuing militants involved in attacks in Israelis.

"Yesterday in Bethelehem we demonstrated once again that the state of Israel will continue to pursue and strike all murderers with Jewish blood on their hands," Barak said.

Israel held Hamas responsible for the rocket attacks because it controls the Gaza Strip.

"When another group takes responsibility for a rocket launch, they are subcontracting out for Hamas," government spokesman Mark Regev said. "No one could be firing rockets from Gaza without the support of Hamas."

Regev had no comment on an Army Radio report that Egyptian intelligence chief Omar Suleiman was due in Israel next week to try to advance truce efforts. Israel has publicly denied that any informal cease-fire was taking shape, though officials have privately acknowledged that Egyptian-brokered attempts were underway.

On Thursday, former Israeli Deputy Defense Minister Ephraim Sneh said Hamas had to be toppled before rocket fire would stop.

"Israel will not exist side with this Iranian entity 3 kilometers (2 miles) from Sderot and 10 kilometers (6 miles) from Ashkelon," Sneh told Army Radio. "There can be no solution without a diplomatic agreement, and there can be no solution without the military wiping out Hamas."

A statement from the office of moderate Palestinian President Mahmoud Abbas, Israel's partner in troubled peace negotiations, condemned Israel's "ugly crime" in Bethlehem.

"The Palestinian Authority holds the government of Israel responsible for all the consequences resulting from these brutal crimes against our people," the statement said.

The latest spiral of violence began just hours after Hamas' prime minister in Gaza, Ismail Haniyeh, called for a period of calm with Israel. Before the Bethlehem raid, there had been signs Israel and Hamas were moving closer toward a cease-fire - including an ebb in fighting after clashes in previous weeks killed more than 120 people, nearly all of them Palestinians.

But Haniyeh spoke before the raid - and it was clear from his speech that his conditions for a truce include a halt to Israeli military operations in the West Bank as well as Gaza.

"We are not going to divide Gaza and isolate Gaza from the rest of the land of Palestine," he said. "Gaza and the West Bank are part of the Palestinian homeland."

In related news, a Palestinian gunman who killed eight students at a Jerusalem seminary last week was buried late Wednesday, Israeli police spokesman Micky Rosenfeld said.

Police had held the body of Alaa Abu Dheim until his family agreed to hold a low-key funeral without media coverage, fearing a mass funeral could spiral into a riot by militant supporters. The burial took place without incident, in the presence of a small number of relatives, Rosenfeld said.

Abu Dheim, a 25-year-old resident of east Jerusalem, was shot dead at the scene of the attack by an off-duty army officer living nearby. No group has claimed responsibility for the attack, but Israeli officials suspect Hamas or Lebanese Hezbollah guerrillas might have been behind it.

A Palestinian news agency says it has received a statement from a group apparently linked to Hezbollah that claimed responsibility for the Jerusalem attack.

Earlier this week, the Maan agency published a photo of the Jerusalem gunman, dressed in a military uniform, along with a statement it said it had received from a group calling itself "The Free Galilee Brigade, Imad Mughniyeh Group."

Imad Mughniyeh was the Hezbollah military chief killed last month in a mysterious explosion in Damascus. Hezbollah has blamed Israel for Mughniyeh's death.

The recent weeks of violence have seriously strained efforts to wrest a final peace deal between Israel and the Palestinians by the December 2008 target they set.

Retired U.S. Lt. Gen. William M. Fraser III, the American envoy monitoring peacemaking progress, is scheduled ot hold his first joint meeting with Israeli and Palestinian officials on Friday, Palestinian officials said.

Palestinian negotiator Saeb Erekat said the Palestinians would ask Fraser to pressure Israel to halt construction in east Jerusalem and the West Bank, lands they claim for a future state.