Gordon Brown is facing urgent calls to clarify remarks during prime minister’s questions when he appeared to suggest Britain and the world economies were in depression.

The Conservatives are demanding Mr Brown explain whether his use of the word was a slip of the tongue or signals the global recession is set to worsen.

“The prime minister must personally and urgently clarify whether his statement today that the world is in ‘depression’ was a slip of the tongue, or whether he knows something that we don’t know,” shadow chancellor George Osborne said.

“For the sake of confidence he should clear up this confusion. Prime ministers in particular need to be very careful about their use of language to ensure they don’t undermine confidence.”

During PMQs on Wednesday Mr Brown said: “We should agree as a world on a monetary and fiscal stimulus that will take the world out of… depression.”

Although it was unclear whether the prime minister meant to say ‘recession’ instead of depression, he did not correct himself and the remark was missed by David Cameron across the despatch box.

The use of the word depression is significant as it indicates a sustained downturn across several economies considered more severe than a recession.

Speaking on BBC2′s Daily Politics show this afternoon, Olympics minister Tessa Jowell said it had been a “slip of the tongue”.

Downing St told inthenews.co.uk it was in the process of clarifying the prime minister’s remarks.

If it proves to be a slip of the tongue, it is not the first time it has happened to Mr Brown during PMQs.

Last December he provided sketch-writers with plenty of ammunition when he told MPs the government had “saved the world”.

Responding to a question about recapitalisation he had said: “We not only saved the world…”, with his attempts to correct himself with “saved the banks” drowned out by the opposition benches.

“Well, it’s now on the record,” Mr Cameron said in reply. “He is so busy talking about saving the world, he has forgotten about the businesses of this country.”