Huda Salih Mahdi Ammash, the only woman included in the US military's list of 55 most-wanted Iraqi fugitives, was taken into custody in Baghdad by US troops, said the official, speaking on condition of anonymity.

Ammash was designated as No 53 on the list and was the five of hearts in the US military's deck of cards of wanted Iraqis.

The moniker 'Mrs Anthrax' was given to Ammash by Western journalists. Anthrax is a bacterial disease that can be used as a biological weapon by spreading its extremely resilient powdery spores.

Ammash, 49, earned a doctorate in microbiology from the University of Missouri in 1983. She had earlier earned a master's degree from the Texas Women's University.

The official said Ammash may be knowledgeable about Iraq's chemical and biological weapons program. She is believed to have been a member of the Baath Party's regional command.

Ammash is one of two well-known women linked to Saddam's weapons programs. The other is Rihab Taha, nicknamed 'Dr Germ'. Taha is not listed among the top 55 most wanted Iraqis.

Both are believed to have worked in Iraq's biological weapons development program and also ascended to senior positions in Saddam's Baath Party leadership.

Ammash has been pictured at cabinet meetings in Saddam's government. In one image, she was seen seated next to Saddam's son Qusay.

Ammash was identified as a key figure in rebuilding Iraq's weapons of mass destruction program after the 1991 Gulf War. She also was a dean at the University of Baghdad.

She has also written about the effect on the Iraqi people of economic sanctions imposed following Saddam's 1990 invasion of neighboring Kuwait.