Gordon Brown does not think the world is in a depression and comments suggesting otherwise were a slip of the tongue, his spokesman has said.
At prime minister's questions he told MPs: "We should agree as a world on a monetary and fiscal stimulus that will take the world out of r... depression."
The Tories urged him to clarify his comments and be careful with language.
Mr Brown and Tory leader David Cameron also clashed over the PM's "British jobs for British workers" pledge.
Speaking after prime minister's questions, shadow chancellor George Osborne said: "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.
"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."
But the prime minister's spokesman told the BBC Mr Brown did not think the world was in a depression. Asked if it was a slip of the tongue, the spokesman replied that that could be inferred.
Asked about the remark later, Housing Minister Margaret Beckett told BBC Radio 4's World at One programme: "I think people have been tossing around discussions about whether it's depression, recession and so on.
"I heard on the news George Osborne had said this was a harmful thing to say, I can not believe the cheek of this man who has done nothing except make negative remarks and try and talk Britain down."
On Monday, Treasury Financial Secretary Stephen Timms warned the country was "facing some of the harshest economic conditions for decades, perhaps for a century".
The apparent mistake follows another slip of the tongue by Mr Brown in December, when he said at prime minister's questions "we not only saved the world" when he meant to say "banks".
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