RAMALLAH, West Bank ? Israeli troops exchanged fire with guards at Yasser Arafat’s office Sunday, and two Palestinian suicide bombers blew themselves up, killing at least 14 people and wounding more than 40 in separate attacks in an Israeli port city and a Jewish West Bank settlement.

The afternoon blasts brought to five the number of suicide bombing in five days. The blast in Haifa ripped open a large hole in the roof of the Arab-owned Matza restaurant, outside the Grand Canyon shopping mall. The explosion shattered tables, blew out windows and covered the floor with twisted piles of metal.

Sunday’s back-to-back explosions were expected to accelerate a major Israeli offensive in Palestinian areas. Israel launched the campaign last week in response to a string of bloody attacks on Israeli civilians. On Sunday, there were first signs of unease in Israel that the military offensive had not been defined in time and scope.

Arafat, besieged by Israeli forces at his compound in the West Bank town of Ramallah, told foreign visitors that the Palestinians are “in urgent need of international forces.”

The Islamic militant group Hamas said it carried out the attack in Haifa to avenge Israel’s incursion into Ramallah. “We will continue the martyrdom attacks on Israel until the full withdrawal from Palestinian territory,” Hamas announced over mosque loudspeakers in the West Bank refugee camp of Jenin.

The assailant was identified as Shadi Tubasi, 22, a resident of the camp. A rival claim by the Islamic Jihad group could not be confirmed.

Witness Shimon Sabag described the horrific scene of “watching people on fire” and being unable to help them all. “I couldn’t deal with the critical injuries, so I turned to the moderate,” Sabag told Israel Radio. “I tried to put out the fire. Even the moderate injured were on fire.”

Police said 14 people were killed and more than 40 wounded in the afternoon blast in the mixed Arab-Jewish city.

Later Sunday, a suicide bomber blew himself up in a paramedics’ dispatch station in the Jewish settlement of Efrat in the West Bank. He killed himself and wounded four members of an intensive care unit, including a trainee medic who was in critical condition.

David Baker, a spokesman for Israeli Prime Minister Ariel Sharon, said that Israel will have to break “this chain of terror” and will use whatever means necessary “to achieve this at the earliest opportunity.”

Earlier Sunday in Ramallah, Israeli troops exchanged fire with Arafat’s guards, who shot from inside the Palestinian leader’s office. Since Friday, troops have surrounded Arafat’s three-story office building, where the Palestinian leader is a virtual prisoner holed up with scores of aides and guards.

Israel said troops opened fire after an armed man stepped out of Arafat’s office building. The Palestinians said Israeli forces fired first and stormed the building, but were pushed back by Arafat’s guards. Israel strongly denied a Palestinian claim that soldiers entered the building.

Arafat was just a few yards from the battling forces, and several of his guards sustained injuries, including two who were in serious condition, said Palestinian security officials inside the compound. They said Israeli troops also fired tear gas, and reported hearing the sound of an explosion.

Israeli Foreign Minister Shimon Peres said Israel has no intention of harming Arafat. “We don’t want to turn it into a world war, into a regional war. We don’t want to turn the entire world against us,” Peres said.

However, the Israeli army spokesman, Brig. Gen. Ron Kitrey, acknowledged that Arafat was at risk, even if he was not a target. “We must remember that he (Arafat) is not sitting in a monastery. He is surrounded by armed people, including his guards,” he told Israel Radio.

Israeli forces enforced a strict curfew Sunday in Ramallah and moved from house to house, looking for suspected militants. The Palestinian Red Crescent said the bodies of four Palestinians were found in downtown Ramallah. An Associated Press reporter saw two bodies lying in a street in the center of the city, near 15 Palestinians kneeling against a wall under Israeli army guard.

On Friday and Saturday, at least 11 Palestinians were killed in fighting with Israeli troops, including two Arafat guards killed in fighting in his compound.

Israel’s ambassador to the United Nations, meanwhile, said U.S. officials have suggested that despite a U.N. Security Council resolution demanding an Israeli withdrawal from Palestinian territory, Israel would not have to act immediately because there’s no timeline.

“Everyone is aware of this, including the Americans,” the ambassador, Yehuda Lancry, told Israel Army Radio.

Later Sunday, Sharon was to convene his Cabinet to decide on the next steps of Israel’s military offensive.

In a first stage of the military campaign, troops took over Ramallah on Friday, including most of Arafat’s sprawling government compound. It was widely expected that other Palestinian towns would be targeted next. Kitrey, the army spokesman, said the operation could take weeks or months.

Israel has called up 20,000 reserves soldiers in the largest mobilization in a decade. The call-up was expected to cost the Israeli economy more than $100 million a month, the Haaretz daily said.

In Israel, signs of unease about the military operation emerged.

Peres, a member of the moderate Labor Party, said the military plans presented to the Cabinet last week were not detailed enough to allow ministers to make an informed decision. Peres and another Labor Party minister abstained in the crucial vote.

“I want to know exactly what is the scope, how far we’re going, for how long, before I raise my hand,” Peres said.

Some newspaper commentators said the military campaign was mainly driven by Sharon’s overwhelming need to settle a personal score with Arafat, who in 1982 was besieged by Sharon’s forces in Beirut, but was able to leave Lebanon with thousands of fighters.

“This explains Sharon’s tremendous urge to humiliate Arafat, a humiliation that makes little sense, other than to satisfy an old desire for revenge,” Nahum Barnea wrote in the Yediot Ahronot daily.

However, President Bush strongly backed Israel, saying: “I fully understand Israel’s need to defend herself.” But speaking at his ranch in Crawford, Texas, Bush said that Arafat “can do a lot more to prevent attacks” against Israelis.

Violence erupted in September 2000, destroying peace negotiations and helping bring the hardline Sharon to power. In the past 18 months, 1262 people have been killed on the Palestinian side and on 401 on the Israeli side.