TRIPOLI, Lebanon — Lebanese army tanks pounded a shadowy group suspected of ties to Al Qaeda yesterday, targeting its hideouts inside a Palestinian Arab refugee camp after hours of clashes killed at least 22 soldiers and 17 militants.

The violence between the army and the Fatah al-Islam group erupted both in the northern port city of Tripoli and the adjacent Nahr el-Bared refugee camp. It added further instability to a country already mired in its worst political crisis between the Western-backed government and Hezbollah-led opposition since the end of the 1975–90 Lebanese civil war.

It was the most serious fight the army had engaged in Lebanon in more than a decade and the worst violence to hit Tripoli in two decades.

Hundreds of Lebanese applauded the army’s tough response in a sign of the long-standing tensions that remain between some Lebanese and the estimated 350,000 Palestinian Arabs who have taken refuge in Lebanon since the creation of Israel in 1948.

The Lebanese Broadcasting Corp. TV station reported that among the dead militants were men from Bangladesh, Yemen, and other Arab countries, underlining the group’s reach outside Lebanon.

Fatah al-Islam is an offshoot of the pro-Syrian Fatah Uprising, which broke from the mainstream Palestinian Arab Fatah movement in the early 1980s and has headquarters in Syria, Lebanese officials say.

It is believed to be led by Shaker al-Abssi, a Palestinian Arab who was sentenced to death in absentia in July 2004 by a Jordanian military court after being convicted of conspiring terrorism in a plot that led to the assassination in Jordan of an American diplomat, Laurence Foley. Al Qaeda in Iraq and its former leader, Abu Musab al-Zarqawi, were blamed for the killing.