A Downing Street spokeswoman said it had always been his intention that he would go only for the closing ceremony - when Britain accepts the Olympic torch from China ahead of the 2012 Games in London - and that the move did not represent a boycott.

"Our reasons for going are exactly the same as they have always been. We still think it is the right thing to do. There is no change in our position," said the spokeswoman.

Mr Brown's decision was applauded by Democratic presidential candidate Hillary Clinton, who has called on President George Bush to boycott the opening ceremonies.

"I wanted to commend Prime Minister Gordon Brown for agreeing not to go to the opening ceremonies of the Olympics in Beijing," she said.

"That was an important decision by Prime Minister Brown and I am calling on Senators McCain and Obama to join me in my request that President Bush also not attend the opening ceremonies."

Meanwhile, Liberal Democrat leader Nick Clegg urged Mr Brown to press the Chinese to abandon plans for the Olympic torch relay to go through Tibet, in the face of bitter opposition from Free Tibet campaigners.

"From his reluctance to bring up human rights during his recent visit to China, to his last minute agreement to meet the Dalai Lama, the Prime Minister has failed to show real leadership on this vital issue," he said.

"He should now follow his decision not to attend the opening ceremony by insisting that the Chinese quickly enter into negotiations with the Dalai Lama and abandon the needlessly provocative plan to parade the torch through Tibet."