DAMASCUS, Syria (AP) _ While allied forces seek to crush Iraq's military power, a shaky alliance of exile groups opposed to Saddam Hussein wait to move into Baghdad if the political structure also crumbles.

But some anti-Saddam leaders fear the inherent differences between the groups - ranging from Communists to autonomy-minded Kurdish guerrillas to Islamic fundamentalists - could plunge postwar Iraq into civil strife.

''I'm getting increasingly concerned about the future every day,'' said one opposition figure, who spoke on condition of anyonmity.

''There are differences among us. We have a common goal in getting rid of Saddam. But there are going to be problems between us,'' said Jalal Talabani, veteran leader of the Patriotic Union of Kurdistan who has fought the Baghdad regime for years.

Indeed, there is a range of objectives, ideologies and visions among the 17 factions that formed a united front last December in Damascus. But the squabbles were papered over by the groups, which saw the growing international condemnation of Iraq as their best chance in many years to join forces and overcome Saddam.

The fundamentalists want to establish an Iranian-style Islamic republic in Iraq. The Communists, liberals and nationalists want a secular Iraq.

The main Kurdish guerrilla groups have presented themselves as a political alternative to Saddam and his Arab Baath Socialist Party, pledging democratic elections and reforms.

Hadi al-Mudarressi of the Islamic Labor Organization says he would bow to an Iraqi government with a non-fundamentalist majority, but would still ''struggle from within to form an Islamic republic.''

A Europe-based opposition figure who requested anonymity, scoffed: ''It's like taking your marriage vows while making plans in your head for a divorce.

''I think the coalition's life expectancy is very short because all those who signed the declaration of unity didn't do it out of any real conviction, but out of self-interest,'' the opposition leader said.

Iran backs a Shiite Muslim grouping led by an Iraqi cleric, Ayatollah Mohammed Bakr Hakim, who has headed a government-in-exile in Tehran for years. Thirty members of his family have been killed by Saddam's secret police.

The Saudis favor the Independent Nationalists led by former Iraqi army commander Maj. Gen. Ibrahim Abdul-Rahman Abu Daoud, who led an abortive coup in 1968.

The Syrians support Gen. Hassan Naquib, a former deputy chief of staff purged by Saddam in 1970 who has been living in Damascus since 1978. He is also a former military advisor to PLO Chairman Yasser Arafat.

About 250 opposition figures from all the factions are expected to meet, possibly in Europe, early next month to try to thrash out a combined manifesto.

But there are problems already.

The Syrian-backed factions, the Kurds and the Iranian-based groups such as the secretive ad-Dawa Islami, or Islamic Call, consider themselves the true resistance. They look down on the groups and anti-Saddam Iraqis individuals operating from Europe.

When Talabani and other members of the Damascus coalition's executive committee visited Saudi Arabia recently they objected to what they considered a Saudi effort to foist the European-based groups on them. They refused to meet with King Fahd in protest.

The Shiites, who form 55 percent of Iraq's 17 million population, would clearly be well placed to dominate any post-war political structure.

But the Kurds, with tens of thousands of armed men, could hold the key. New regimes in Baghdad traditionally try to win the Kurds over and any new government that excludes them faces trouble.

Another potentially troublesome factor is that any government installed in Baghdad if Saddam is ousted will likely be seen in the Arab world, as well as by many Iraqis, as a U.S. puppet.