The cyanide salt was in either one or several small bricks, and U.S. officials said they believe it was to have been used in an attack on U.S. or allied interests. Cyanide is extremely toxic and can be used as a chemical weapon, although it was unclear if the cyanide was in a form that could be used that way easily.
The raid took place on Jan. 23, a defense official said, speaking on condition of anonymity. It was unclear if anyone was captured in the raid. Parts for making bombs also were found in the house, the defense official said.
The house was inhabited by a suspected subordinate of Abu Musab Zarqawi (search), U.S. officials said. Zarqawi is a Jordanian whom CIA officials have described as a senior associate of Usama bin Laden (search).
Zarqawi is believed to have tried to direct Al Qaeda operations inside Iraq, although it is unknown if he is in the country now.
He also is connected with Ansar al-Islam (search), an Islamic extremist group from northern Iraq. He and his followers are believed to have sought cyanide and other chemical weapons for use in attacks in the past, American officials say.
U.S. officials say they have mounting evidence to suggest Zarqawi has had a hand in multiple attacks in Iraq, including those on a mosque in Najaf, the U.N. headquarters in Baghdad and Italy's paramilitary police station in Nasiriyah.
Another alleged Al Qaeda member, Hassan Ghul, detained this year while trying to enter northern Iraq, is believed to have met with Zarqawi to plan attacks against U.S. and coalition forces, said another U.S. official speaking on condition of anonymity.
Now in U.S. custody, Ghul is believed to be cooperating with interrogators. He is known as a facilitator who can move people and money around and is the highest-ranking member of to Al Qaeda have been arrested in Iraq.
The U.S. official said Ghul also is thought to have worked closely with Khalid Shaikh Mohammed, who officials say masterminded the Sept. 11, 2001, attacks.
The official said attacks in Iraq for which Zarqawi is a suspect include a truck bomb in August that hit U.N. headquarters in Baghdad, killing 23 people; a car bomb that exploded outside a mosque in Shiite Muslim holy city of Najaf and killed more than 85; and a suicide truck bombing in November that devastated Italy's paramilitary police headquarters in southern city of Nasiriyah, killing more than 30.