Shiites Under Siege

* Who: Shiite Muslims comprise about 55% of Iraq’s 17.5 million people. This is the second largest Shiite population in the region, after neighboring Iran’s.

The other Muslim sect, the Sunnis, are the majority worldwide but the minority in Iraq, representing about 15% of the population. President Saddam Hussein and his ruling circle are Sunnis. Kurds, who are mostly Sunni, make up about 25% of the population. About 5% of the population are Christians or members of other sects.

* Where: The schism in Islam that gave rise to the Shiites and Sunnis occurred in the 7th Century in what is modern-day Iraq, making it the spiritual center of the world’s estimated 100 million Shiites. Iraqi cities with major Shiite populations are in the southern part of the country.

* Recent History: At the end of the Persian Gulf War in 1991, Shiite rebels rose up against Hussein. Without substantial support from the allied coalition, the Shiites were crushed by government forces. About 200,000 rebels fled to the marshes of extreme southern Iraq, inaccessible to tanks and ground forces.

Hussein has massed forces outside the marshes and undertaken massive projects to build roads into the area. There are reports of bombing of Shiite villages and refugee areas, in violation of U.N. cease-fire bans on military air traffic in Iraq and repression of civilians.

Shiite opposition leaders in exile have tried to draw international attention. With other Iraqi opposition leaders, they were given a high-level reception in Washington last month and said they were assured of help, possibly enforcement of the ban on air flights over their region or establishment of a monitored haven.

* New Developments: Britain announced that the Gulf War allies plan to bar Iraqi warplanes and helicopters from southern Iraq. Hussein would risk military reprisal for air attacks in the zone.