Brown and Cameron clash over who is the closest to Obama

The Prime Minister claimed Mr Obama's triumph was based on "progressive policies" similar to Labour's action on the banking crisis, the minimum wage and its emphasis on government regulation.

But Mr Cameron said Americans had voted for change and Britons also wanted a new regime to make a fresh start in tackling the recession.

The Tory leader was withering about Mr Brown's decision not to call a snap election last autumn, as well as his recent claim that a recession was no time for a novice.

He told Labour MPs: "You've made your strategic choice. It's called more of the same and it's sitting in front of you. You killed change when you bottled that election and you buried change when you appointed Peter Mandelson. I read this morning that the Prime Minister has sent a message to the president-elect. Presumably, it wasn't 'this is no time for a novice.'"

Mr Brown countered: "What I said was that serious times need serious people.'"

To Labour cheers, the Prime Minister added that Mr Cameron had changed his stance on borrowing to combat the recession in recent weeks. "The only change that they [the Conservatives] represent is that they change their minds every week," he said.

At Prime Minister's Questions, Mr Brown told MPs he sent his "sincere congratulations" to the US president-elect, who would be a "true friend to Britain".

Mr Cameron also congratulated Mr Obama on his "stunning victory" but insisted Mr Brown, in contrast, could not provide "the change people want" in this country.

Tory MPs chanted: "Change! change!" as they tried to shout down Mr Brown, who countered: "The truth is that the Conservative Party policies are rejected in America and in Britain."

He added: "I know Barack Obama and we share many values. We both have determination to show that government can act to help people fairly through these difficult times facing the global economy."

London's Mayor Boris Johnson welcomed the US election result, saying: "Barack Obama is unquestionably the right man for the job. This election will restore the faith of all those who believe in America."

And around the world political leaders paid tribute to the president-elect. French president Nicolas Sarkozy said: "At a time when we must face huge challenges together, your election has raised enormous hope in France, in Europe and beyond."

German chancellor Angela Merkel said Europe and the United States would work together "in a spirit of mutual trust."

In Afghanistan, president Hamid Karzai hailed a "new era". He added: "I applaud the American people for their great decision."

But the war which faces Mr Obama carried on, with a US airstrike near Kandahar in which dozens of women and children were feared dead.

Russian President Dmitry Medvedev said he hoped Mr Obama would "make a choice in favour of full-fledged relations with Russia".

Iran's government-run daily paper said: "Defeat for Republicans is the price they pay for Bush's strategic and tactical blunders."