Scotland Yard detectives are expected to interview Tony Blair within a few weeks in an attempt to conclude their highly sensitive investigation into the cash for peerages allegations.

	Tony Blair is expected to be interviewed in weeks

The six-month investigation moved significantly closer to Downing Street with the confirmation yesterday that detectives had questioned one of Mr Blair's senior aides under caution.

Ruth Turner, 36, the director of government relations at Downing Street, was interviewed last week about e-mails and documents relating to allegations that peerages and other honours were used to reward businessmen who gave Labour money or loans on advantageous terms.

Three people have been arrested during the inquiry, including Lord Levy, Mr Blair's chief fund-raiser.

The police are under pressure from MPs to finish next month when Parliament returns.

But detectives have decided that Mr Blair will not be interviewed until all the others have been questioned and they are ready to present their conclusions to the Crown Prosecution Service.