Nato's secretary general has warned that anti-Americanism could have serious consequences for international relations.

Lord Robertson warned in a documentary to be broadcast on Monday that "an unreasoning and emotive" attack could lead to the US withdrawing from the international community.

"I'm very worried about anti-Americanism because I think it is deeply corrosive to a relationship that is critically important for the overall security of the world," he told the BBC.

"I see disengagement being the outcome and that being much more dangerous to all of us than American involvement or interventionism."

Foreign secretary Jack Straw also voiced concerns at "trite" anti-Americanism.

"I think that people get obsessed about the United States because of its immense wealth and power. I think it's just become fashionable, this kind of anti-Americanism, and it's a convenient parody," he said.

"If you look at the United States of course there are things that we would not necessarily approve of, but if you look at the US's contribution to where we are today, it has been immense and for the good."