After Iraq warned that it would use unconventional means to try and retake the airport, Air Marshal Brian Burridge told BBC's Newsnight programme: "It may be one of two things."

"An attack with chemical or biological weapons -- that would have very serious consequences for the regime in that it would be met with a proportional response and those responsible would be held to account," he said.

"Secondly, he could use a human tide and we had signs last night (Thursday) that there were loudspeakers in south-west Baghdad signalling people should rise up and march on the airport," he said.

"That was pretty much in character to use civilians in that way as human shields in a way that might put them in danger," he said.

Earlier Friday, Iraqi Information Minister Mohammad Said al-Sahhaf warned: "Tonight we will carry out something that is not conventional against them, not military. It will be a great example to them."

The US military said its troops seized control of the strategic prize of Baghdad's international airport on Friday and were flushing out remaining pockets of resistance.

SPACE.WIRE