WASHINGTON – Since the formal search for weapons of mass destruction in Iraq was called off in January 2005, the American military has found more than 500 shells of ordinance containing Sarin or mustard gas.

While the shells are believed to date from the Iran-Iraq war, two Republican lawmakers are saying it raises enough questions for the president to order a new search for the biological, chemical and nuclear weapons program he said Saddam Hussein was concealing from the international community before the invasion of Iraq.

“The information released today proves that weapons of mass destruction are, in fact, in Iraq,” Senator Santorum, a Republican from Pennsylvania said yesterday. “It is essential for the American people to understand that these weapons are in Iraq. I will continue to advocate for the complete declassification of this report so we can more fully understand the complete WMD picture inside Iraq.”

Pentagon officials, however, yesterday said the weapons disclosed in the partially declassified Army’s National Ground Intelligence Center report were “not the weapons we were looking for.” Indeed, unexploded chemical ordinance dating from before 1991 are different from the stockpiles of anthrax and other toxins the then Secretary of State, Colin Powell told the U.N. Security Council in January 2003 was awaiting inspectors in Iraq.

That said, under the terms of the 1991 cease-fire that ended the shooting part of the Gulf War, Iraq was obliged to account for and destroy the stocks of chemicals and germs he had acknowledged to have amassed prior to the invasion of Kuwait which sparked the Gulf War.

The latest information about the chemical weapons shells, however, is most damaging to those who suggest the work of former weapons inspectors David Kay and Charles Duelfer have provided the definitive word on the whereabouts of the suspected WMD, according to the chairman of the House Permanent Select Committee on Intelligence.

“Duelfer after 18 months was not able to find this stuff,” Mr. Hoekstra said. “We made this determination that hundreds [of weapons] were found. I think this is a significant quantity. What does this say about all of the other issues that continue to be raised [such as] stuff transported to Syria. I don’t believe everything that is out there is credible, but it shows how much we still don’t know.”

Indeed, Mr. Duelfer’s final report said numerous sites were ransacked before inspectors got there and there were reams of documents that his team did not analyze. Mr. Hoekstra said he did not consider yesterday’s declassified findings to be a “silver bullet,” nor was he prepared to get into details about what was in the new report.

Other former intelligence officials have said that some old ordinance from the Iran-Iraq war was left on the battlefield.