In separate interviews, all of the scientists said they were involved in civilian research projects and none knew of any programs for weapons of mass destruction. It was not clear why their materials, ostensibly for nonmilitary research, were ordered destroyed.
But their accounts indicate the government of Saddam Hussein may have had advance knowledge of at least some of the inspectors' visits.
"An hour or two before the inspectors came to the university, I got my orders from the chairman," said a biochemistry professor at Saddam University for Science and Engineering.
"The order was to hide anything that might make the inspectors suspicious. Any bacterium, any fungus. I destroyed seven petri dishes…and I put the others in the trunk of my car."
He said the petri dishes held Staphylococcus and E. coli bacteria and a fungus that can cause severe skin problems — all commonly used for experiments.
A university dean denied that he ordered any destruction or concealment.
President Bush claimed during his State of the Union address that Iraqi spies had penetrated the U.N. inspections. While some inspectors privately suspect as much, none of the inspection teams found any firm evidence to support the president's claim.
"Clearly we were well aware that the Iraqis were trying to figure out our inspection plans and we took many practicable precautions against that," said Ewen Buchanan, spokesman for the U.N. inspectors.
He said information was handled on a "need to know" basis and precautions included "silent briefings" between inspectors to elude any listening devices the Iraqis may have placed at U.N. offices in Baghdad.
U.N. inspectors returned to Iraq last November after a four-year hiatus. They conducted hundreds of visits to factories, universities and military facilities.
Despite the insistence of the Bush administration that Iraq had chemical, biological and nuclear weapons programs, the inspectors found no such evidence before the U.S.-led war on Iraq forced them to leave in mid-March.
So far, U.S. forces haven't found any conclusive evidence that Iraq has weapons it was banned from possessing after the 1991 Gulf War. Officials hope scientists and other Iraqis will feel free to provide information now that the regime is gone.
None of the scientists interviewed by the AP in their homes and on campuses said they had any such information to provide.
But four graduate students in the biotechnology department at Saddam University said they too received orders from their department head to get rid of bacteria.
They claim to have been told to remove media for culturing bacteria and shaker-incubators used for fermentation. Such laboratory equipment, used by scientists to grow bacteria for study, could theoretically be used to create biological agents such as anthrax.
But the equipment would be much too small to generate biological weapons in the quantities Iraq has been accused of producing.
In arguing for war over the past months, the Bush administration contended not only that Iraq had weapons but that it had massive quantities, including materials that could produce over 25,000 liters of anthrax and more than 38,000 liters of botulinum toxin.
That means that finding an isolated set of WMD material or equipment might not be a big enough "smoking gun" to convince war skeptics.
The U.S. government is sending more than 1,000 experts specializing in weapons, intelligence and computers to join the hunt.
But the Washington Post reports analysts are worried that their list of suspected sites might turn up empty.
After some of the best leads have tested negative, their hope of finding weapons increasingly rests on accidental finds. Troops are being sent to guard facilities like government ministries that weren't on the list of suspected sites to protect them from looters or regime agents.
Earlier this week, U.S. military officials, speaking on condition of anonymity, confirmed they found material that could have been used to build chemical weapons.
However, many chemical weapons ingredients have nonmilitary purposes and officials cautioned that the findings, which are being analyzed, do not confirm the presence of chemical weapons.
The find was made several days ago with the help of an Iraqi scientist who claimed to have worked in Saddam's chemical weapons program. He says Iraq destroyed biological and chemical weapons material in the months leading up to the war.