UK warns Russia over nuclear threat

As the United States said that the "escalation" in the Russian rhetoric was "not helpful", Prime Minister Tony Blair's official spokesman said there were concerns across the continent at Mr Putin's increasingly hard-line stance.

The Russian President used an interview with western journalists ahead of this week's G8 summit in Germany to denounce American plans for a missile defence system sited in the former Soviet bloc states of Poland and the Czech Republic.

He warned the US was in danger of sparking a new arms race and suggested Moscow could respond to the perceived threat by targeting Europe for the first time since the Cold War with its nuclear arsenal.

However Mr Blair's spokesman insisted the US system was not aimed at Russia, but was intended to safeguard against the threat of a "rogue state" which managed to acquire a nuclear weapon.

He said the system was in the wrong location and had too few interceptor missiles to defend against an attack from Russia. At the same time, he made plain the disquiet in Western capitals at Mr Putin's belligerent attitude.

"We want to have a constructive dialogue with Russia," he said. "We want to be able to talk about issues such as Kosovo, Iran and other global issues in a constructive way. Equally Europe as a whole does have concerns and will not be shy in expressing those concerns.

"We want a constructive relationship. Whether there is a constructive relationship is as much up to Russia as it is to us."

US national security adviser Stephen Hadley, travelling with President George Bush to Europe said that there had been "some escalation in the rhetoric" coming out of Moscow.

"We think that that is not helpful," he said. "We would like to have a constructive dialogue with Russia on this issue. We have had it in the past."