DOWNING Street has rejected claims by a former senior army officer that the UK has become irrelevant and a "bit player" in attempts to resolve the conflict in Ukraine.

But Labour seized on the remarks of Sir Richard Shirreff, until last year a top Nato commander in Europe, saying they were a damning indictment of David Cameron's leadership.

After branding the Prime Minister a "foreign policy irrelevance," Sir Richard said: "This is the most serious crisis to have faced Europe, arguably, since the Soviet invasion of Czechoslovakia in 1968. There is a threat of total war.

"The UK is a major Nato member, it is a major EU member, it is a member of the UN Security Council and it is unfortunate that the weight that the British Prime Minister could bring to efforts to resolve this crisis appear to be absent."

As the leaders of Germany and France embarked on their diplomatic initiative to Moscow to broke a peace deal for the Ukraine, No 10 sought to play down suggestions of a diplomatic rift, insisting the visit was part of the so-called Normandy Group process, which began during last year's D-Day commemorations, in which France and Germany have taken the lead.

"We have been in regular discussions with our French and German counterparts about that as part of the ongoing Normandy format. It's tended to be France and Germany doing that," said a spokeswoman.

But senior Labour figures seized on the criticism of the PM.

Ed Miliband said: "We do need a British government that is engaged in the problems of the world. It is a pretty damning indictment of his foreign policy that he seems pretty distant and pretty irrelevant.

"It's yet another reason why we need to be an engaged partner in the European Union, not sleepwalking to the exit," insisted the party leader.

Douglas Alexander, the Shadow Foreign Secretary, claimed Sir Richard's comments were a "serious indictment" of Mr Cameron's foreign policy.

"This isn't the first time that his Government has been one step behind our allies in trying to negotiate a diplomatic resolution to the crisis in Ukraine."

The Paisley MP added: "This warning, that he is a 'bit player' in foreign policy, is yet more confirmation that David Cameron is weakening Britain's influence abroad, at the time when it is most needed."