The Australian Senate has rejected a proposed inquiry into a leaked phone conversation between the Australian Prime Minister Kevin Rudd and the US president.

Mr Rudd has refused to answer questions about whether he or his staff leaked information to a newspaper about the phone call.

The Australian newspaper claims George W. Bush had to ask Mr Rudd what the G20 group of rich nations was.

Today, the Senate failed to back Family First party Senator Steve Fielding's proposal for an inquiry into how the information was leaked.

Liberal Senator George Brandis says the Labor Party is avoiding scrutiny by voting against an inquiry.

"Nothing could be more serious than a breach of the security of a conversation between the prime minister and the president of the United States of America, he said.

"As a result of the Labor Party's opportunistic and hypocritical conduct, the opportunity for parliamentary scrutiny has been denied."

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