THE IRAQI NATIONAL CONGRESS (INC)
The U.S.-funded INC is nominally the umbrella organisation for Iraqi groups who long opposed Saddam's rule.
Formed in 1992 by 300 exiled Iraqi politicians, officers and Muslim clerics, it combines more than 30 political groups that include democrats, liberals, secularists, Islamists and Kurds.
In 1996, Saddam sent his forces into Kurdish-held northern Iraq, forcing the INC, said to be plotting a U.S.-backed coup, to shut its offices in the enclave.
With little if any presence in Iraq, its fortunes revived soon after U.S. President George W. Bush came to power in 2001 pledging $97 million to fund the organisation.
The INC is effectively run by London-based Ahmad Chalabi, a businessman with powerful friends in the Pentagon and Congress.
But mistrust of his leadership prompted the emergence of a rival group that includes some INC components.
This is the so-called Group of Four -- two Kurdish parties that control northern Iraq, the Shi'ite Muslim Supreme Council for Islamic Revolution in Iraq (SCIRI) and former members of Saddam's Baath party.
KURDISTAN DEMOCRATIC PARTY (KDP)
Founded by Mustafa Barzani in 1946, the KDP is one of Iraq's oldest opposition groups. Seeking more freedom for Iraq's four million Kurds, it battled Baghdad on and off for decades.
Barzani's son Masoud took over when his father died in 1979. Last year the KDP unveiled a draft constitution for a federal Iraq with autonomy for Kurds.
The KDP has shared control of northern Iraq with the rival Patriotic Union of Kurdistan since the 1991 Gulf War, but fighting between them opened the way for a bloody Iraqi incursion in 1996. The two groups have since patched things up and reopened their regional parliament in October, 2002.
PATRIOTIC UNION OF KURDISTAN (PUK)
The PUK was founded in 1975 in Damascus when its leader Jalal Talabani broke away from the KDP after the 1974-75 Kurdish rebellion collapsed. Last September, the PUK agreed with the KDP on a draft constitution, outlining the structure of a regional administration and envisaging the oil-rich city of Kirkuk as capital of a Kurdish region to be part of what Talabani said would be a "democratic, pluralist and federal Iraq."
Talabani, 70, enjoys good relations with Iran and Saudi Arabia. He also meets U.S. and Turkish officials regularly.
SUPREME COUNCIL FOR ISLAMIC REVOLUTION IN IRAQ
SCIRI is led by Iran-based Ayatollah Mohammad Baqir al-Hakim whose father, Grand Ayatollah Muhsin al-Hakim, was a senior Shi'ite cleric until his death in 1970. SCIRI, which has frozen its membership in the INC, has a 70-member assembly representing six Islamist groups and scholars from Iraq's Shi'ite community.
IRAQI NATIONAL ACCORD (INA)
Ayad Allawi, a British-educated neurologist who defected from Iraq's Baath Party in the late 1970s, formed INA in 1990 with the apparent support of Kuwait and Saudi Arabia.
After shuttling between Kurdish areas, Syria and Jordan, Allawi, who has good ties with Washington, settled in London. INA is made up mostly of defectors from the military and intelligence services, and belongs to the Group of Four.
IRAQI NATIONAL COALITION
The Iraqi National Coalition groups several small factions headed by former officers. Its leader is Major-General Tawfiq al-Yassiri, who led mutinous units in the Shi'ite revolt against Saddam in southern Iraq after the 1991 Gulf War over Kuwait. He was wounded and escaped to the West through Saudi Arabia.
His group is in contact with other officers in exile, such as former chief of staff General Nizar Khazraji and former military intelligence chief Major-General Wafiq al-Samarrai.
IRAQI NATIONAL FRONT
This U.S.-based political group says it is allied with a number of other opposition forces seeking to establish a democratic and constitutional Iraq, with free elections and a market economy. "Once this becomes a reality, the Iraqi National Front hopes Iraq will be turned into something like a Malaysia or Singapore of the Middle East," it said on its website.