Lord Janner told an inquiry he had no contact with a convicted child abuser despite another probe finding there was an "abundance of evidence" the pair knew each other, according to reports.
The former MP was interviewed about Frank Beck - a care home manager and prominent social worker in Leicestershire - following the latter's conviction for prolific child abuse in 1991.
According to the BBC, documents released through Freedom of Information requests show that Lord Janner denied having been in touch with Beck when he appeared before the 1992 inquiry into Beck's years of abuse at children's homes.
An inquiry by Sir Richard Henriques that concluded in January 2016 found "there was available an abundance of evidence that Janner knew Beck", and that "all of this would have been supporting evidence discrediting Janner".
Allegations that Lord Janner, who died in December 2015, sexually abused children over a period spanning more than 30 years and dating back to the 1950s are currently being being examined as part of the wide-ranging Independent Inquiry into Child Sexual Abuse, chaired by Justice Lowell Goddard.
Beck, who died in prison, had shouted Janner's name out in court in February 1991 when he appeared before magistrates charged with child abuse.
After Beck's conviction, the then-government ordered an inquiry into Leicestershire Social Services, and the probe's chairman Andrew Kirkwood QC questioned Lord Janner in 1992.
According to the BBC, the peer was asked by Mr Kirkwood: "Your contacts with Mr Beck would have been to what extent?"
Lord Janner replied: "Nil", except for one occasion when he said Beck might have answered a telephone call.
Sir Richard wrote in the conclusion to his report: "It is significant to note that at the Kirkwood Inquiry, between January and June 1992, Janner stated that he did not know Beck and that between 1975 and 1986 ... he had no contact with him.
"There was considerable evidence collated during Operation Magnolia to the effect that Janner was a regular visitor to Children's Homes and that he had a number of dealings with Beck.
"All of this would have been supporting evidence discrediting Janner and, thus, supporting the prosecution case."