Bush was talking privately to British Prime Minister Tony Blair during a lunch at the Group of Eight summit in St Petersburg about an upsurge of violence in the Middle East, not realizing a microphone was transmitting what he said.

"I think Condi (Secretary of State Condoleezza Rice) is going to go pretty soon," Bush said.

Blair replied: "Right, that's all that matters, it will take some time to get that together." Rice said on Sunday she was thinking of going to the Middle East if it would help.

Blair said Rice has "got to succeed" if she goes to the region. Bush replied: "What they need to do is to get Syria to get Hezbollah to stop doing this shit."

It's not the first time the unwary President, who claims to be a born-again Christian, has been caught cursing. He called a New York Times reporter a "son of a bitch" to an open mike, told Wall Street Journal reporter Al Hunt "fuck you" in front of his daughters.

The U.S. president blames Syria and Iran for supporting Hezbollah guerrillas operating in southern Lebanon.

Bush also seemed to complain about U.N. Secretary-General Kofi Annan wanting an immediate ceasefire to stop the violence between Israel and Hezbollah.

"I don't like the sequence of it," Bush said. "His attitude is basically ceasefire and everything else happens."

Blair said: "I think the thing that is really difficult is you can't stop this unless you get this international presence agreed."

G8 leaders, in a statement on Sunday, suggested the U.N. Security Council should consider an international security and monitoring presence along the Lebanese-Israeli border.

Later, Bush said he felt like telling Annan to telephone Syrian President Bashir Assad "and make something happen."

"We're not blaming Israel and we're not blaming the Lebanese government," he said.

The two leaders also appeared to chat about the Doha Round of world trade talks, stalled by lack of common ground among governments on farm subsidies and intellectual property rights.

"I just want some movement. Yesterday I didn't see much movement, the desire to move," said Bush.

"It may be that it's impossible," Blair replied.

Ultimately Blair noticed the microphone and hastily switched it off, but not before the recording had reached news media.

In the chummy conversation between long-time allies, Bush teased the British leader about a sweater Blair had apparently given him.

"Thanks for the sweater, it was awfully thoughtful of you. I know you picked it out yourself," Bush said.

"Oh, absolutely," said Blair.

(Reuters news service contributed to this report)