Taha Yassin Ramadan, who served as vice president under Saddam Hussein, was handed over to U.S. forces in Mosul on Tuesday, the U.S. Defense Department said.
Ramadan also served on Saddam's Revolutionary Command Council member and was known as "Saddam's knuckles" for his ruthlessness. He was No. 20 on the U.S. most-wanted list.
Pentagon spokeswoman Chief Petty Officer Diane Perry confirmed that he had been turned over to the U.S. Army Tuesday.
Al-Jazeera, the Qatar-based satellite broadcaster, said Ramadan was captured by troops of the Patriotic Union of Kurdistan Tuesday. He was wearing peasant clothing as a disguise, the broadcaster said.
Ramadan, 65, was widely considered as ruthless as Saddam. He headed a 1970 court that executed 44 officers for plotting to overthrow the regime. He worked as a bank clerk before Saddam's revolution. He came from the Mosul region.
He was Saddam's vice president beginning in March 1991. During a visit to Jordan in the 1980s, Muslim fundamentalists asked Ramadan what the Baath's attitude to Islam was. Muslims were free to pray and follow their faith, Ramadan replied, "but if they try to harm the Baathist regime or ridicule its slogans, the regime will break their necks!"
Ramadan is high on the list of regime figures Iraqi opposition groups say should be tried for war crimes.
President Bush responded to Ramadan's capture during a conversation with reporters near his vacation home in Crawford, Texas, reports CBS News Correspondent Mark Knoller.
"Slowly but surely we're getting those remnants of the Saddam regime," the president said.
The Pentagon says 38 of the 55 most-wanted Iraqis have been captured or killed, including 13 of the top 20.
Born in 1938, he joined the underground Baath Party in 1956 and became close to Saddam. After the 1968 coup by the party, he held several ministerial posts and became a member of the regional command in 1969.
During the 1980s, he was deputy prime minister and was for a time considered the second most powerful man in Iraq after Saddam.
Latif Rashid, a spokesman for the PUK in London said he was notified of the capture by PUK forces in a telephone call from the PUK spokesman in Sulaymaniyah.
"He was hiding among his relatives or colleagues," he said.
In Sulaymaniyah, PUK official Kasrat Rasouli confirmed that Ramadan was captured by the PUK, but would give no other details.
He was said to have provided over many purges carried out by Saddam to eliminate rivals and strengthen his political control.
He lauded the execution of Iraqi officials found guilty of bribery as necessary "lessons for the others" and often took a harder line than Saddam in denouncing the United States, Israel and other states deemed hostile to Baghdad.
He once described the U.S. Congress as little more than an extension of Israel's Knesset, or parliament.
For all his ruthlessness, Ramadan obeyed Saddam in all things.
Shortly before the end of the 1980-88 war with Iran, Saddam ruled that too many Iraqi officials were getting fat while the troops at the front were fighting for the nation's survival.
He published the weights of his Cabinet ministers and the weights he felt they should be, then gave them 30 days to slim down. The flabby Ramadan was told to shed 60 pounds — and did.