NAHR EL-BARED, Lebanon -- The Lebanese army unleashed a torrent of firepower yesterday on a Palestinian refugee camp that is home to a militant group loyal to al-Qaida, amid fears that the two-day-old conflict could spread and undermine a government already beset by political schism.
The fighting has claimed at least 50 lives and was the worst internal conflict since Lebanon's 15-year civil war ended in 1990.
Fighting erupted in another Palestinian refugee camp in the south, and a bomb exploded in an upscale Sunni Muslim neighborhood in the capital, injuring six people. It was unclear whether the incidents were linked to the fighting here in the north.
By last night, the military had ceased shelling the camp.
A spokesman for the militant group, Fatah al-Islam, told wire services that if the army siege did not stop, militants would step up attacks elsewhere.
Inside the Nahr el-Bared camp yesterday, dead fighters lay in the streets as snipers from Fatah al-Islam crouched on rooftops. Several buildings had been destroyed by shelling. Wounded civilians could not be treated because electricity and water had been cut off, residents said.
"The human situation is a catastrophe," said Fatah Deeb, a doctor inside the camp. "We were not able to carry out any surgical operation," he said before his phone went dead.
Red Cross officials said they were able to retrieve at least 17 injured civilians during a brief cease-fire that was broken before aid workers could establish a presence inside.
Experts believe Fatah al-Islam has no more than a few hundred fighters, many from other Arab countries. But observers said the group appeared to be using the country's instability to establish a foothold and "institutionalize" al-Qaida in Lebanon.
Lebanon already is a crossroads for conflict. A dozen Palestinian refugee camps house about 400,000 people and have often served as bases for militant organizations. Last year, Israel fought a two-month war against Hezbollah, a radical Shiite Muslim group that controls much of the southern part of the country.
Lebanon also has been divided between a pro-Syrian camp, which includes Hezbollah, and a Western-oriented faction that opposes Syrian influence.
Hezbollah has stayed away from the fray, but on Sunday it issued a statement blaming the government for the country's growing insecurity.
"If the authorities cannot assume the responsibility and protect the citizens and the country, then they should resign," Michel Aoun, a Christian opposition lawmaker allied with the Shiite group, said yesterday.
The government of Prime Minister Fouad Siniora has accused Syria of supporting Fatah al-Islam with weapons and money, a charge denied by the group and Damascus.
President Bush, speaking to the Reuters news agency on Air Force One, said, "Extremists that are trying to topple that young democracy need to be reined in."
He stopped short of accusing Syria of involvement: "I'll be guarded on making accusations until I get better information, but I will tell you there's no doubt that Syria was deeply involved in Lebanon. There's no question they're still involved in Lebanon."
Hezbollah, listed as a terrorist organization by the U.S. State Department, is backed by neighboring Syria, which dominated politics and stationed troops in Lebanon for decades. Siniora's government is split between pro-Syria and anti-Syria forces.
Ahmed Ayoubi, an expert on Islamist groups, said al-Qaida associates have been arrested recently in the northern port city of Tripoli.
"Some members of the group are real Islamists who fought in Iraq and abide by al-Qaida's ideology," he said, while others are locals, motivated by poverty and resentment of the government. "It is not easy to get rid of a group like Fatah al-Islam."
The radical group is led by Shaker al-Abssi, who was released from prison in Syria last year.
Al-Abssi is also wanted by Jordanian authorities, who sentenced him to death in absentia for his alleged role in the assassination of an American diplomat there in 2002.
Authorities say members of the group based in Nahr el-Bared were planning to attack a German train and were behind a February bombing that killed three commuters on a bus going through a Christian area of the mountains above Beirut.
Despite its foothold in Nahr al-Bared, the group appears to have little support inside the camp, which is home to about 40,000 Palestinian refugees.
"The shelling is indiscriminate," said Ashraf Ibrahim, 30, a resident in the camp. "What is our fault? Fatah al-Islam is not part of the camp. They are intruders."
In Washington, a State Department spokesman said the Lebanese army was operating in a "legitimate manner" against "provocations by violent extremists."
"This is a group that has been involved in violence to achieve whatever their stated objective may be," said spokesman Sean McCormack, referring to Fatah al-Islam.
Raed Rafei and Louise Roug write for the Los Angeles Times.