Sydney- Australian Prime Minister Kevin Rudd was asked not once but four times Tuesday to deny that he or his staff had deliberately tried to embarrass US President George W Bush by telling reporters that the leader of the free world had asked him, "What's the G20?" during a private telephone conversation this month.

Rudd's repeated refusals to do so were characterized by opposition Liberal Party leader Malcolm Turnbull as a "serial and eloquent plea of guilty."

The press is off the hook for the slur on Bush, who this week is to host a meeting of the Group of 20 in Washington, because Rudd has not blamed the media and has refused calls for an inquiry into the controversy.

Rudd's office and the White House, both of which had note-takers monitoring the call, have denied that Bush asked Rudd to detail the composition of the G20 group of developed and developing economies.

Pressed in Parliament to deny that he or a staffer had made up a calumny that was passed first to The Australian newspaper, Rudd stayed mum.

Turnbull, a former high-priced barrister, skewered Rudd by saying he had been unmasked in an attempt to present himself as a clever chap and the US president as an ignoramus.

The purported contents of the phone call, Turnbull said, contained "an account so self-serving that it presented him as a diplomatic encyclopedia, a font of all knowledge, and the president of the US, the chief executive of our greatest ally, as a fool."

The opposition said it believes it has Rudd cornered, arguing that a further admission of guilt was an embarrassing tableau in parliamentary question time that had Foreign Minister Stephen Smith fielding questions that the prime minister would not answer. (dpa)