Americans stockpile food and water

Americans rushed to the shops to prepare for a possible new terrorist attack involving weapons of mass destruction.

Stocks of plastic sheeting, heavy duty sealing tape and face masks disappeared almost overnight after the US government warned they should be able to seal their homes from radiation or a biological and chemical attack

The rush was greatest around New York and Washington where stocks of torches and first aid kits are all but exhausted. A superstore outside Washington created its own "homeland security supply department" offering bottled water, plastic sheets and packs of batteries,

Families have been told to create a "safe room" in their homes where they can shelter until authorities can bring the situation under control.

In New York, where authorities have warned of an attack on subways, many commuters are also packing a disposable face mask as a precaution.

The state of alert was raised on Monday from yellow to orange - the second highest warning of an impending terrorist attack.

Security has already been stepped up at airports, with road blocks at bridges and tunnels leading to Manhattan and police carrying rifles in Times Square.

Organisers of an anti-war protest will not be allowed to march past the United Nations in New York on Saturday for security reasons. In Washington, missile launchers are being set up at key sites after warnings of an air attack aimed at inflicting mass casualties on a high profile building in Washington.

The Avenger missile system is in place on Capitol Hill as a war atmosphere grips Washington. Federal officials have told all Americans to make sure they have three days supply of food and water. "This is prudent planning" said Gordon Johndrow, a spokesman for the homeland security department.