Iraqi troops, searching terrorist hideouts in Fallujah, discovered a chemical weapons laboratory with manuals on manufacturing explosives and toxins - including anthrax, according to National security adviser Qassem Dawoud.
Dawoud said National Guard troops "found a chemical laboratory that was used to prepare deadly explosives and poisons."
He said the lab was in a district where pockets of fighters are still holding out following the US led assault on the city.
"We also found in the laboratory manuals and instructions spelling out procedures for making explosives," Dawoud said. "They also spoke about making anthrax."
Dawoud showed pictures of a shelf containing what he said were various chemicals.
The US military said it discovered the "largest weapons cache to date in Fallujah."
The weapons - including anti-tank mines and a mobile bomb-making lab - were found inside a mosque used by an insurgent leader. Troops also found documents detailing hostage interrogations, the military said.
They were in the Saad Abi Bin Waqas Mosque where Sunni rebel leader and imam Abdullah al-Janabi often spoke, the US military said.
Marine officers said they so far have found enough weapons in Fallujah to refuel a nationwide rebellion.
Troops also found what may be a mobile bomb-making factory housed in a truck, as well as mortar systems, rocket-propelled grenades, launchers, recoilless rifles and parts of surface-to-air weapons systems.
The troops also found "documents that detailed insurgent interrogations of recent kidnap victims," the marines said.
US and Iraqi troops continue to sweep the city amid sporadic gun battles with rebel fighters.
A lieutenant of Iraq's most feared terrorist leader Abu Musab al-Zarqawi has been captured in Mosul, Mr Dawoud also claimed.
He named him as Abu Saeed, but he gave no further details.
Al-Zarqawi, whose al-Qaeda-linked group has been responsible for numerous car bombings and beheadings of foreign hostages, including three Americans and Briton Ken Bigley, was believed to have been based in Fallujah. But the Jordanian-born extremist managed to escape the siege.
The United States has offered a $13m reward for al-Zarqawi's capture.
US Secretary of Defence Mr Donald Rumsfeld said US troops, celebrating Thanksgiving after some of their bloodiest weeks in Iraq, should brace for even more losses as they pursue insurgents bent on wrecking an election scheduled for January.