The Prime Minister told detectives on Thursday that he did not have “full knowledge” of secret gifts received by Labour or the subsequent nominations of lenders for peerages, according to senior sources.

Lord Levy had claimed in a written statement that Mr Blair knew about his dealings with the lenders. Lord Levy will now come under intense pressure to explain how and when he told Mr Blair about the loans, and any subsequent knowledge of nominations for peerages.

Mr Blair suggested yesterday that it was “perfectly natural” for the police to have interviewed him. Speaking for the first time about his questioning, he said: “This is a complaint that was made by the Scottish National Party against me personally, in effect, and so it is not in the slightest bit surprising or wrong that the police should want to talk to me.”

Until now, Lord Levy has declined to answer questions in person, instead providing a written account to police with the aid of a solicitor. If he provides specific evidence of conversations with the Prime Minister, Mr Blair could be interviewed again as a potential suspect under caution.

A senior Whitehall source said: “The screws will be turned on Levy because, at the moment, their accounts do not stack up.”

Mr Blair became the first serving Prime Minister to be interviewed by police in a criminal inquiry. He told Scotland Yard detectives that he was unaware of certain details of specific nominations for peerages, who was lending money to Labour, and in what capacity, sources said.

Lord Levy is expected to be interviewed again in the new year.

Other key figures will also be questioned for a second time. They include Jonathan Powell, the chief of staff to Mr Blair, and Ruth Turner, the director of government relations.

Mr Powell is expected to be asked about “e-mail traffic” between him, Lord Levy and Ms Turner. Ms Turner will be questioned about documentation relating to Sir Christopher Evans, the biotech tycoon who lent Labour £1 million. She is understood to have declined to answer some questions.

Police will want to speak to Sir Christopher again. He was arrested in September in connection with the inquiry. Sources indicated that a notebook obtained from Sir Christopher appears to have provided a “smoking gun” for police because it mentions his £1 million loan in connection with a possible honour.

Last night the BBC reported that a note of a conversation between Sir Christopher and Lord Levy contained the question: “Wd you like a K or a big P?”, referring to a knighthood or a peerage. Sir Christopher’s office maintains that there is no record of any offer of a peerage in return for cash and Lord Levy has refused to comment.

Mr Blair emphasised that the nominations for peerages that prompted the inquiry had been made by him as party leader and not as a reward for public service. “That’s the basic distinction that lies at the heart of this,” he said.

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