Continuing clashes between Lebanese army troops and Islamic militants holed up in a Palestinian refugee camp have sparked concerns the deadly violence may soon spread to more of Lebanon's 12 refugee camps. From Beirut, VOA's Margaret Besheer has this report on the militant group at the center of the crisis.

The first time many Lebanese learned of the existence of Fatah al-Islam was in February, when a twin bus bombing outside Beirut killed three people and injured 20 others. The group was linked to the attack. Then last month, they surfaced again when some of their members were charged with a dramatic bank robbery in the northern port city of Tripoli.

Shell explodes on a building being used by militants in the besieged Nahr el-Bared refugee camp near the city of Tripoli

Paul Salem, Director of the Carnegie Endowment's Middle East Center in Beirut says the group's several hundred fighters came to the Nahr El-Bared camp, near the northern city of Tripoli, over the past year.

"It is not clear who exactly is behind them, and I think that is part of the point," Salem said. "Some of these groups are being set up precisely to do those things without them being traceable to someone."

But American University of Beirut political science professor Ahmad Moussalli says they are al-Qaida linked.

"I think definitely. Some of them were trained in Afghanistan with al-Qaida, some of them fought in Iraq," he said. "Abu Musab al-Zarqawi, the famous - or infamous - leader of al-Qaida of Iraq, was affiliated with this group, and he in fact pushed this group to organize itself in Lebanon."

Many theories exist in Lebanon about who is behind Fatah al-Islam. One is that the Future Movement of Saad Hariri, a pro-Western Sunni leader, wanted a Sunni militia to defend against the growing influence of the Shiite Hezbollah movement following last summer's war between Hezbollah and Israel.

Professor Moussalli agrees with this theory.

"Because of last year's war they [Fatah] were encouraged to create a militia," he said. "They were given arms, support, finance and so forth. So they turned from 19 to 20 people to about 1,000 people in about six months. The government wants to try to distance itself from this phenomenon."

But the Carnegie Endowment's Paul Salem strongly disagrees.

"I think that is way off. I don't think that is the case, particularly in Lebanon. In Lebanon the Hariri government is supporting, and has been in a very strong way, the Sunni mainstream, and has moderated the Sunni community tremendously," he said.

Professor Moussalli believes the group is well-financed with money coming from several sources.

"Partly from al-Qaida; partly from Lebanese; partly from Gulf states; partly from religious individuals. I don't think they have trouble getting money, obviously," he said.

So what is Fatah al-Islam trying to accomplish?

The experts say chaos and civil war. Carnegie's Paul Salem:

"I think their goal is to hamstring the Lebanese Army, to destabilize the country and to put pressure on the country and through the country the international community," Salem said.

American University of Beirut political science professor Ahmad Moussalli agrees.

"They are working to create confusion, to create problems, to open up venues for civil war in Lebanon," he said.

Meanwhile, as the standoff with Fatah al-Islam drags into a third week, a second group, Jund al-Sham, have clashed with the Lebanese Army outside the largest Palestinian refugee camp in Lebanon.

The clashes at the southern Ein el-Hilweh camp have sparked fears that fighting could spread to some or all of Lebanon's 12 Palestinian refugee camps.

Professor Moussalli says he is not surprised that the violence has spread.

"This was expected. Because Fatah al-Islam is a splinter group that started with Jund al-Sham," he said. "So they are not removed or far away from them ideologically; organizationally. Some of the Fatah al-Islam leadership came from Jund al-Sham in Ein al-Hilweh camp."

Professor Moussalli says regional problems - such as the Arab-Israeli conflict and the Iraq war - in addition to internal Lebanese troubles, have allowed such militant groups to take root and flourish in Lebanon.