Ministers will be answering their phones more nervously after it emerged that Margaret Beckett was fooled into embarrassing indiscretions by impressionist Rory Bremner.

The Foreign Secretary was apparently taken in when Bremner called on the eve of the last General Election pretending to be Gordon Brown.

Mrs Beckett - Environment Secretary at the time - is said to have entered into detailed discussions with the comedian over fellow ministers' prospects and who should be given what role following the poll victory.

Unaware the exchange was being taped, she advised Brown' against bringing former Trade Secretary Stephen Byers back into the Cabinet.

She also agreed then-Trade Secretary Patricia Hewitt was "out of her depth", and suggested John Prescott should have his powers scaled down.

However, the production team on Bremner, Bird and Fortune decided against broadcasting the extraordinary conversation for "regulatory reasons".

Mrs Beckett insisted she had "no recollection" of the conversation, but did not rule out being the politician involved.

She also said Bremner would be guilty of an "unprincipled and unpleasant breach of privacy" if the claim was true.

"I've never given my phone number to Rory Bremner, nor knowingly had such a conversation with him," she said.

"I have no recollection of a conversation in the terms that are being suggested.

"If he has done as he suggests, it is both an unprincipled and unpleasant breach of privacy."