US Defense Secretary Donald Rumsfeld has said air strikes alone will not be enough to destroy Iraq's alleged weapons of mass destruction.

You don't believe everything you read in the newspaper, do you?

US Defense Secretary Donald Rumsfeld

As media speculation continues about alleged US plans to attack Iraq, Mr Rumsfeld told a news conference in Virginia that the main problems were that many of Iraq's chemical, biological and nuclear arms sites were "deeply buried" and highly mobile.

"A biological laboratory can be on wheels in a trailer and make a lot of bad stuff. And it's movable and it looks like most any other trailer," Mr Rumsfeld said in response to a reporter's question on why the US did not simply bomb the sites.

"So the idea that it is easy to simply go do what you suggested ought to be done from the air is a misunderstanding of the situation."

His statement also coincides with growing criticism of US plans by countries in the Middle East - the latest by King Abdullah of Jordan who is visiting Washington.

Media frenzy

Mr Rumsfeld said that the Iraqis had learned how to conceal the "precise actionable location" of military targets and that they had "an enormous appetite for nuclear weapons".

King Abdullah warned US attack would open a "Pandora's Box"

He refused to say how US might deal with such arms depots, but again critised a media reports speculating about Washington's military options.

"You don't believe everything you read in the newspaper, do you?" he said when asked about a report in the Washington Post that many US military chiefs wanted to continue the current policy of "containment" of President Saddam rather than forcefully removing him.

US analysts have warned that a possible US invasion - involving possibly hundreds of thousands of troops and hundreds of aircraft - could result in high casualties.

The New York Times has recently reported that Washington was studying the idea of seizing the capital, Baghdad, and key command centres and weapons depots to topple President Saddam.

Both President Bush and Mr Rumsfeld have said the media speculation could place US soldiers at risk.