Downing Street has played down David Blunkett's suggestion he is helping John Prescott take key decisions while Tony Blair is on his annual holiday.
Mr Blunkett is one of the senior cabinet members
Work Secretary Mr Blunkett said he was helping to explain the government's proposed new laws to tackle extremism.
But Downing Street said: "The deputy prime minister is in charge while the prime minister is on holiday".
The spokesman added Mr Prescott had talked to colleagues like Jack Straw at the weekend but not to Mr Blunkett.
Tony Blair last week outlined a raft of plans to extend powers to deport or exclude foreigners who encourage terrorism.
Ex-Home Secretary Mr Blunkett said he was working with Deputy Prime Minister John Prescott to cover "a whole range of issues while other good colleagues are taking a break".
He said he was explaining to the UK public "about what it is we are facing, and why we are taking the additional steps".
"I obviously have the experience and the knowledge and I help out in terms of having to take, with John Prescott, the necessary decisions in the next couple of weeks," he said.
But he insisted: "Hazel Blears substitutes for the home secretary, she is his deputy and she is doing extremely well."
On Tuesday minister Ms Blears said she, not David Blunkett, was in charge at the Home Office while Mr Clarke is away on holiday.
Ms Blears is minister for policing, security and community safety.