The Prime Minister's wife Cherie Blair was said to be deeply unhappy after reading predictions that she is to have her baby delivered by Caesarean section.

Labour life peer Lord Winston made the revelation - which he later denied - in an interview with the New Statesman magazine, sparking extensive media coverage of his remarks.

Despite the peer's denials, the New Statesman insisted it stood by everything written by interviewer Mary Riddell, and said she had tapes of Lord Winston's comments.

The BBC's World at One programme, which played a copy of the recording on Friday, said Lord Winston could be heard to refer to Mrs Blair's pregnancy.

Mrs Blair was 'very upset' by the reports, the Prime Minister's official spokesman said.

But he added: "He (Lord Winston) is adamant he did not discuss Cherie, he doesn't know about Cherie's pregnancy.

"He doesn't know if she is having a Caesarean. Neither does anybody apart from her and her family and doctor and that is the way it should stay."

Mrs Blair had so far been able to have check up and scans without publicity and she wanted to "keep it that way", he added.

Lord Winston denied making the comments about Mrs Blair as controversy flared up on Friday.

He said he had not spoken about Mrs Blair's pregnancy and said he did not know whether she would need a caesarean.

But the New Statesman's deputy editor Cristina Odone said: "I have spoken to Mary and everything is on tape, including the comments about Cherie. We stand by everything she wrote."