A Labour donor who loaned the party £1m may have been asked by the party's chief fundraiser whether he wanted a knighthood or peerage, it has emerged.
Lord Levy, Labour's chief fundraiser, has denied any wrongdoing
The BBC has learned notes made by Sir Christopher Evans about conversations with Lord Levy suggest he was asked if he wanted "a K or a big P".
Nothing other than the notes suggest that Lord Levy, who has denied any wrongdoing, made the remark.
Sir Christopher's spokesman denied the offer of an honour for cash was made.
On Thursday police asked Tony Blair about the notes of conversations between his Lord Levy and the Labour donor.
The prime minister's questioning was not under caution, meaning he is not a suspect.
Sir Christopher, a successful biotechnology businessman who was knighted in 2001, was arrested four months ago by police investigating the cash for honours affair.
He gave the party £1m as a loan in 2005.
The BBC can now reveal that in the notes Mr Blair was questioned about - which were shown to several witnesses - Sir Christopher recorded that Lord Levy asked him if he wanted "a K or a big P".
This has been deemed to be an apparent reference to a knighthood or a peerage.
The note is understood to stem from the period in which Sir Christopher received his knighthood.
A spokesman for Sir Christopher denied that there was a record of an offer of an honour in return for cash, because he said such an offer was never made nor sought.
He said he had been told by police that neither his OBE nor his knighthood were under investigation.
The BBC put the allegations to Lord Levy, who refused to comment.
He has publicly vigorously denied any wrongdoing.
In a statement following the peer's arrest in July, his lawyer Neil O'May said: "Although any allegations remain unclear, Lord Levy wants everyone to understand that he has not been involved in any wrongdoing or assisted anyone else in any wrongdoing."
Privately friends of Labour chief fundraiser say he has never offered anybody anything.
BBC politics editor Nick Robinson said no charges have been made in the cash for honours investigation and there may never be any.
He said if charges were to be made "the police will have to find evidence and prove it in court of a link between cash offered or given and honours received or offered".
Appointments to the House of Lords are under scrutiny
Referring to the latest note, our correspondent said: "Both men and their friends tell me... that this is the world that they occupy, that they live in a world where people talk all the time about honours - in part of course because they make substantial donations not just to political parties but to charities too.
"That's all this might be. It is up to the police to work out if it is more than that or if it's just an intriguing and extraordinary insight into an extraordinary world."
Meanwhile, Chancellor Gordon Brown has attacked any attempt to link him to the cash-for-honours affair as ''unfounded allegations and smears''.
His remarks follow suggestions that he proposed giving peerages to two political allies who had given Labour money.
And Mr Blair, who became the first serving prime minister to be interviewed by police pursuing a criminal investigation, has said it had been "perfectly natural" that officers had chosen to speak to him.