Lord Steel, the Liberal Democrat peer, has admitted believing in 1979 that child abuse allegations against Sir Cyril Smith were true, but did nothing to assess whether he was a continuing risk to children.

The former Liberal party leader said the late MP for Rochdale confirmed in a conversation that reports of child sexual abuse in the media were accurate.

But rather than suspend and investigate the MP, Steel allowed him to continue in office. Smith stepped down as an MP in 1992 and died in 2010.

Steel’s astonishing statement was made at the independent inquiry into child sexual abuse on the day it was criticised as a waste of money by the Conservative leadership hopeful Boris Johnson.

Steel, 80, has previously appeared to deny knowing whether Smith was a child abuser. In an interview with the BBC’s Newsnight last year, he said the allegations were “scurrilous hearsay”.

Richard Scorer, a specialist abuse lawyer at Slater and Gordon, said Steel’s failure to act upon Smith’s confession was “an extraordinary dereliction of duty”.

“Smith went on to abuse boys at a care home in the 80s. If Steel had taken action in 1979 and stripped Smith of his power and status then that abuse would probably have been prevented,” Scorer claimed.

Under questioning, Steel said he confronted Smith about the allegations of child sexual abuse in 1979 after reading them in Private Eye magazine.

A series of young boys in Rochdale children’s homes had claimed that their local MP had stripped, spanked and bathed their buttocks and on occasion fondled their genitals, the magazine claimed.

Steel told the inquiry he questioned Smith about the allegations during a meeting in the House of Commons. “What I said to him was: ‘What’s all this about you in Private Eye?’

“He said, rather to my surprise, ‘It is correct’ that he had been in charge of or had some supervisory role in a children’s hostel, that he’d been investigated by the police, and that they had taken no further action, and that was the end of the story,” the peer said.

The allegations of sexual assault against Smith were investigated by Lancashire police in 1969 but no action was taken.

Steel said that he did not question Smith further about specific child abuse claims but concluded that the allegations were true.

Inquiry counsel Brian Altman QC asked: “So you understood that he’d actually committed these offences, from what he said to you?”

Steel responded: “I assumed that.”

Steel said he did not ask the party to launch any form of formal inquiry into Smith because the alleged incidents took place before Smith was voted in as an MP in 1972. He also said he did not seek any further advice on the allegations or discuss them with colleagues.

Altman suggested: “He could for all you knew still be offending against children.” Steel said: “I have to admit that never occurred to me and I am not sure it would occur to me even today.”

Des Wilson, a former Liberal party officer, told the inquiry in a statement that Smith was a “monstrous character” who intimidated Steel.

Wilson wrote: “I have no idea why no action was taken after the Private Eye article, but then I was not around and perhaps Steel did discuss it with him, though Steel’s natural tendency, in my view, would be to hide his head in the sand rather than get involved in a nasty confrontation.”

Steel said Wilson’s statement was a “pardonable exaggeration”. He also denied Wilson’s claim that the party could not afford another sex scandal so soon after the Jeremy Thorpe affair, in which the previous Liberal leader was accused of trying to murder his male lover.

The hearing heard that Steel passed a recommendation that Smith should receive a knighthood in 1988, which was successful. Steel said he did not mention his conversation about sexual abuse to the honours committee.

“It never occurred to me to tell the honours committee about it. It was all, in a sense, in the public domain through Private Eye,” he said.

In a June 2018 appearance on the BBC’s Newsnight programme, he described child sex abuse allegations against Smith as “tittle-tattle”. Steel told the hearing he thought he was referring in the interview to claims made in a book by former Rochdale MP Simon Danczuk.

In 2014, Danczuk, in his co-authored book Smile for the Camera: The Double Life of Cyril Smith, claimed the politician had been left free to abuse children as young as eight, despite 144 complaints by victims.

Six years ago, police apologised after concluding that Smith should have been charged on three separate occasions in the 1960s and the 1990s for a series of indecent assaults.