A top Pentagon official says the discovery of a single artillery shell in Iraq containing a deadly nerve agent could be a significant find or it could be "nothing."

Defense officials have confirmed that an artillery shell planted as a roadside bomb in Iraq and discovered this month did contain the deadly nerve agent Sarin.

However, the Pentagon also says testing has revealed the device was made by Iraq before the 1991 Gulf war, leaving unanswered the question of whether Saddam Hussein produced any weapons of mass destruction more recently.

Still, Pentagon spokesman Larry Di Rita said that the find could be significant, though he conceded it is too early to say. ?This could be a very big deal,? he said. ?It's just too early to tell. There's obviously a lot more interest in trying to determine if there is another stockpile of these shells out there.?

Mr. Di Rita went on to say he is not dismissing the find just because it is a single shell of pre-Gulf war manufacture. ?I certainly don't dismiss it as well, it's pre-war and no big deal, because it could be lot more,? he added. ?It could be nothing and it's just too early to tell.?

U.S. forces invaded Iraq last year, citing the threat posed by Iraq's weapons of mass destruction. So far no stockpiles of chemical or biological weapons have been found.

The shell found in Baghdad this month was used as a roadside bomb by anti-coalition insurgents who apparently were unaware it contained Sarin. Because there was no major explosion as there might have been with a conventional artillery shell, U.S. officials say there was only a minor release of the nerve agent. Two American soldiers who dealt with the device suffered only low-level exposure to Sarin.