NUCLEAR missiles intercepted by America's "Son of Star Wars" project could hit the UK instead, a leading scientist has claimed.

Physicist Ted Postol, of the Massachusetts Institute of Technology, made his claims in the influential New Scientist magazine today.

He says the project, which would make use of the North Yorkshire listening stations at Fylingdales and Menwith Hill, could allow warheads from rogue states to plunge to earth way short of their US targets - possibly on Britain.

The system is supposed to intercept missiles minutes after launch, while their rocket boosters are still burning.

But Dr Postol says that destroying only the booster could leave the warhead intact and still flying across the sky.

Where the warhead lands could be anywhere between the launch site and the target city.

A missile fired at the U.S. from Iraq, for instance, might fall short and land on Britain, he claimed. "Even if you knew all the details, you couldn't be sure of what would happen in any given engagement," said Mr Postol.

His warnings were today backed by North Yorkshire peace campaigner Helen John, who said: "If this man is correct, and the missiles could fall short and land on us, we are in the firing line, even more so than the U.S.

"We know this system won't work anyway. They tested the interception missile, knowing exactly where the target would be, and they still got it wrong. How can we expect them to hit something they don't know is coming? And then, can we trust what will happen to the warhead after that? I don't think so."

Fellow campaigner Anni Rainbow said: "Of course this guy has a point. If you attack the boosters, you leave a warhead flying around ready to fall anywhere."

Scientists say intercepting burning boosters is easier than tracking a relatively cool and easily-disguised warhead high above the atmosphere. The "boost-phase interception" project could use a laser, mounted on a modified Boeing 747.

The beam could burn a hole in the thin skin of a missile booster, but would not destroy a tough warhead designed to withstand the heat of re-entry.

Geoff Forden, also from the institute, said: "The guys who might launch this thing probably won't care enough to say 'If it doesn't hit New York, I don't want to launch it at all'."

Updated: 16:56 Thursday, February 07, 2002