Rice: I'm in charge of Middle East peace not Blair

Dr Rice made it clear she was in charge of brokering peace between the Israelis and Palestinians, not the former prime minister.

She said Mr Blair should instead stick to his narrow remit of mending the Palestinian economy and political system, a role merely complementary to her job as leading peacemaker to the region.

Her comments will embarrass Mr Blair, who has been angling for a more prominent role from the Quartet, the peacemaking body of the U.S., UN, EU and Russia.

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When he was appointed Middle East envoy on the day he left office on June 27, Mr Blair had pledged to broker a Northern Ireland-style peace process between Israel and the Palestinians.

This contrasted with his predecessor, former World Bank president James Wolfensohn, who dealt solely with Palestinian economic reform.

But on Mr Blair's first day in the job, Dr Rice insisted the U.S. would keep leading Middle East peace efforts, with Mr Blair playing a 'completely complementary' role.

'There is also a political track that for a variety of reasons the U.S. is committed to lead in coordination with the Quartet,' she said before a meeting of the peacemaking body in Lisbon.

She later told Sky News that Mr Blair would bring 'an energy' to improving the lives of Palestinians, describing him as an 'experienced, capable, historic figure'.

Israeli government spokesman Mark Regev said, however, that while he had no doubt Mr Blair would make a difference, no one believed he could 'show up and be the Messiah and suddenly everything will fall into place'.

Liberal Democrat foreign affairs spokesman Michael Moore said the fact that Dr Rice was playing down Mr Blair's role 'indicates that the Quartet is in a mess and the Palestinians and others are right to be highly sceptical about it'.

Mr Blair will make his first visit to the Middle East in his new role next week.

The job is unpaid - although it comes with office expenses of around £100,000 - meaning Mr Blair has been forced to look elsewhere for a way of funding his post-Downing Street career.

He plans to bolster his earnings on the lecture circuit and last week he was the star guest at a media and technology conference in Idaho.