Aziz, who had been in hiding since the fall of Baghdad, is one of the few Iraqi leaders widely recognizable in the West because of his history as a diplomat at the United Nations.
His prominence in the regime could make Aziz a source for the best information yet on the fate of Hussein and his two sons, as well as the location of any hidden weapons of mass destruction.
"We can confirm Tariq Aziz is now under coalition control," said Central Command spokeswoman Capt. Dani Burrows.
Graham, at a session of the Council on Foreign Relations, declined to identify the Iraqi, saying only that he held one of the most sensitive positions in the Iraqi government and was arrested in the past 24 hours.
Aziz was often the public face of Iraq when responding to accusations by the United States and United Nations.
He was the only Christian in Hussein's inner circle, most of whom were Sunni Muslims like Hussein. He served as foreign minister during the 1991 Persian Gulf war and was a frequent spokesman at that time.
Aziz last appeared in public March 19, when he held a news conference in Baghdad to quash rumors he had fled the Iraqi capital.
"I am carrying my pistol to confirm to you that we are ready to fight the aggressors," Aziz said then. "American soldiers are nothing but mercenaries and they will be defeated."
Although he was one of Hussein's most loyal aides, Aziz, like most non-Tikritis, had virtually no power, U.S. officials have said. That could explain his longevity in Hussein's inner circle - without an independent power base, he posed no threat.
In recent years Aziz did not have the international profile he had in the 1990-1991 gulf crisis when, as Iraqi foreign minister, he was virtually "Mr. Iraq" to the world's media.
Hussein promoted him after the gulf war to deputy prime minister, forcing him to relinquish the foreign ministry portfolio. Some believe this reshuffle had to do with Hussein's not liking a Cabinet minister to become too well known.
Others point to the fact that Hussein's son Odai did not like Aziz. Odai's newspaper, Babil, often criticized foreign policy. In 1996, Aziz's son Ziad was arrested for corruption in what Baghdad insiders saw as a turf battle between Ziad and Odai, who was equally known for graft.
However, Tariq Aziz retained weight within the government. He was Hussein's deputy on the foreign affairs and media committees, in which positions he interpreted Hussein's policies to the ministers concerned. He also conducted the government's negotiations with the U.N. weapons inspectors.
When Hussein fired Aziz's replacement as foreign minister, Mohammed Said al-Sahhaf, in 2001, he appointed Aziz as acting foreign minister for four months until Naji Sabri was given the post.
Al-Sahhaf's new post was as Iraq's information minister, which he used during the latest war to denounce the U.S.-led invasion and famously deny that American troops were in Baghdad after they had already captured the capital's international airport.
Born in 1936 near the northern city of Mosul, Aziz studied English literature at Baghdad College of Fine Arts and became a teacher and journalist. He joined the Baath Party in 1957, working closely with Hussein to overthrow British-imposed monarchy.
Aziz changed his name from Mikhail Yuhanna. In Arabic, Tariq Aziz means "glorious past."
As American troops searched for other survivors of the fallen Iraqi government, the American administrator of Iraq, Jay Garner, announced that an interim Iraqi government would be in place next week.
In his announcement, the administrator, a retired lieutenant general, declined to specify how the interim body would be chosen. He did, however, say that Ahmad Chalabi, the Iraqi exile who arrived in the capital before Garner and has been asserting himself in the past 10 days, was not the coalition's official candidate.
Despite Garner's assurances, the political situation in the capital and throughout the country was murkier than ever.
Political unrest simmered in the Kurdish areas in the north, where Arabs were expelled from their homes by Kurds, and in the southern city of Kut, a Marine command post was shot at in two incidents. No one was hurt, according to a military spokesman, but the shootings followed a standoff Wednesday between protesters who support a local ayatollah, and a convoy of 20 U.S. military vehicles.
In the capital last night, bursts of automatic weapons fire - much more than on other recent nights - sounded through the city as darkness fell.
The man who had appointed himself mayor of Baghdad, Mohamed Mohsen Zobeidi, took little heed of Garner's presence yesterday. A day after he was brusquely rebuffed by the chief American military officer here, Lt. Gen. David McKiernan, Zobeidi was nonetheless the center of attention at a gathering of hundreds of people at a tribal sheikh's luxurious villa in the southern Daura district of the capital. A team of experts has been sent to the region to look into suspicions that some of the more than $600 million found in cash, part of it hidden behind walls in one of Saddam Hussein's palaces, might be counterfeit, Secret Service officials said in Washington.
Of the new government body, Garner said: "It will have Iraqi faces on it. It will be governed by the Iraqis." Of Chalabi, he said: "Mr. Chalabi is a fine man. He is not my candidate; he is not the candidate of the coalition."
Despite Garner's words about Chalabi, he was having dinner with him last night.
One of the main arguments in Washington, where the details of a new Iraqi government are being debated, is the role of Chalabi and whether he should be granted a prominent position or one alongside many others. Chalabi has backing from the Pentagon, including some training for a force of armed exiles he brought with him.
Speaking at his first news conference in the capital, Garner said he was concerned about the influence of Iran at anti-American demonstrations by religious Shiites in the past few days.
Echoing warnings from the Bush administration to Iran not to meddle in Iraq, Garner said: "It concerns me that I'm being told Iran is playing a role."
Without being specific, the general said that U.S. forces in Iraq would not allow "external influences to come in."
Garner brushed aside the suggestion that Iraq, where about 60 percent of the population are Shiites, could become an Islamic republic. The United States insisted on one thing - democracy - in the formation of a new government, he said.
Given that bottom line, he said, it was difficult to "think how a Islamic Republic would be a democratic process."