Labour's deputy leader Tom Watson "has a lot of questions to answer" over his public comments about sex abuse allegations against former Conservative minister Lord Brittan, Prime Minister David Cameron has said.
Mr Cameron said the West Bromwich East MP should "examine his conscience" after Lord Brittan's brother called on him for an apology.
Mr Watson accepted on Friday that he should not have repeated the comment of an alleged sex abuse survivor that the peer was "close to evil".
But he insisted it was his "duty" to pass on testimony from those claiming to have been abused to the Director of Public Prosecutions (DPP).
Demands for an apology came after a senior Scotland Yard officer wrote to Lord Brittan's widow last week to apologise for failing to tell the family before the peer's death in January that he had been cleared of allegations that he raped a 19-year-old woman in 1967.
Asked during a visit to Devon whether Mr Watson should apologise, Mr Cameron told LBC radio: "It's clear I think that he's got a lot of questions to answer and the House of Commons Select Committees are quite rightly going to ask him some questions so I'm sure he should answer those questions and examine his conscience about whether he's said enough so far."
The chairman of the Commons Home Affairs Select Committee has indicated that the influential cross-party panel will decide on Tuesday whether to call Mr Watson to give evidence
Responding to demands for an apology from Lord Brittan's brother, the journalist Sir Samuel Brittan, Mr Watson said that he contacted the DPP in 2014 because he felt the allegations he had been made aware of against Lord Brittan "should be fully investigated".
The MP stated he was sorry for the "distress Leon Brittan's family experienced as they grieved for him" as a result of the claims.
And he added: "As the tributes flowed in from his lifelong friends I felt for those people who claimed he abused them.
"I repeated a line used by one of the alleged survivors, who said, 'He is close to evil as any human being could get'. I shouldn't have repeated such an emotive phrase.
"The choice facing anyone who is presented with testimony of this kind is whether to pass it on to the authorities and urge them to investigate or to ignore it.
"I chose the first option. I felt it was my duty to do so."
Mr Watson said he believed Lord Brittan "would have been interviewed even if I hadn't intervened because the DPP made it clear in her reply to my letter that the police investigation into him was ongoing".
The Crown Prosecution Service (CPS) found in July 2013 that there was not enough evidence for a prosecution, but the decision was never passed on to the peer.
The case was reopened last year after Mr Watson wrote to the DPP and police later interviewed Lord Brittan under caution, when he was seriously ill.
Shadow culture secretary Michael Dugher hit back, writing on Twitter: "Would Cameron prefer to go back to the days when allegations about child abuse were ignored by the establishment and swept under the carpet?
"If you chose to ignore serious allegations, rather than have them properly investigated, you would indeed need to examine your conscience."