A former Labour MP accused of multiple child sex offences made official visits to parliament even though he had been diagnosed with dementia so severe that he could not stand trial.

Lord Janner visited Westminster three times even though medics had declared him not fit to stand trial due to his condition. Documents released to the Mail under the Freedom of Information Act show he used his own car and security pass on May 27 last year, one month after the medical ruling.

He also used the car park on June 2 and 3, with a spokesman at the House of Lords confirming the peer was there on official business that month.

Labour MP Simon Danczuk questioned how Janner was well enough to visit parliament on official business given his diagnosis: “I was told by police that Lord Janner was alleging ill health in April 2014 so he couldn’t be interviewed,” he said. “To hear that he was on official parliamentary business two months later is astonishing.

“If the CPS and police were aware of this then they surely would have taken a decision to interview him. How can Lord Janner be fit enough to be on official parliamentary business, but not fit enough to answer questions about extremely serious crimes?”

In April this year, Allison Saunders, director of public prosecutions, announced police had gathered enough evidence to charge Janner with 22 offences between 1969 and 1988 involving nine children. However, due to his earlier diagnosis he would not be able to stand trial.

Since then, numerous questions have been raised as to how severe Janner’s condition really is.

Last month he was photographed out for a stroll in London, while it also emerged that since his condition was first diagnosed in 2009 he has voted 209 times in the House of Lords.

Alleged victims have also announced plans to pursue Janner in civil court. Liz Dux of Slater and Gordon said: “We are going to keep fighting. We are going to pursue a civil claim. It will not be a class action but a series of individual claims.”

“They will be significant claims because these people have had their lives ruined,” she added.

The allegations against Lord Janner are just the latest in a series regarding the Westminster establishment. Claims of a “child sex ring” involving senior politicians in the 1980s centre on various locations such as Dolphin Square in Pimlico, London.

However, charges have yet to be brought and many alleged offenders have so far not been named.