Mr Cheney said Ms Pelosi should leave foreign policy to Mr Bush

Mr Cheney also told a radio station that Ms Pelosi bungled the delivery of a message from Israeli PM Ehud Olmert.

Ms Pelosi told Mr Assad Israel was "ready to engage in peace talks". Israel later said this was contingent on Syria ending "support for terror".

A spokesman for Ms Pelosi said she had made it clear the issues were linked.

The top Democrat met Mr Assad in the Syrian capital, Damascus, on Wednesday, before moving on to Saudi Arabia.

'Nonsensical statement'

After the talks, Ms Pelosi said she was pleased with assurances that she had received from the Syrian leader.

Pelosi in Mid-East press

"He's ready to engage in negotiations for peace with Israel," she said. "The meeting with the president enabled us to communicate a message from Prime Minister Olmert that Israel was ready to engage in peace talks as well."

But a statement from Mr Olmert's office later said that Ms Pelosi's comments did not indicate any change in Israeli policy.

"To carry out real peace negotiations Syria must cease its support for terrorism," the statement said.

Mr Cheney said that the Israeli reaction indicated the message had not been authorised.

"It was a non-statement, nonsensical statement and didn't make any sense at all that she would suggest that those talks could go forward as long as the Syrians conducted themselves as a prime state sponsor of terror," he said.

"I think it is, in fact, bad behaviour on her part. I wish she hadn't done it."

But Brendan Daly, a spokesman for Ms Pelosi, said that she accurately relayed a tough message that included a demand for Syria to "eliminate its links with extremist elements".

Washington accuses Syria of backing Palestinian group Hamas and Lebanon-based Hezbollah, two groups it says are terrorist organisations.

The Bush administration has also boycotted Syria since the 2005 murder of Lebanon's former PM Rafik Hariri, accusing it of involvement.

But the bipartisan Iraq Study Group recommended last year that the US should begin direct talks with both Iran and Syria to find a way to end insurgent and sectarian violence in Iraq.