The decision not to prosecute Greville Janner for historical child sex offences is to be overturned, according to reports.

A barrister who has spent several weeks examining the evidence as part of an independent review has concluded there should be a hearing of the allegations, the Daily Mail has claimed.

The decision is expected to be released next week and would overturn the Crown Prosecution Service’s decision in April not to pursue Lord Janner.

Such a move would pave the way for evidence to be tested in a criminal court in a “trial of facts”, and will put Alison Saunders, the director of public prosecutions, under pressure to resign.

Simon Danczuk, the MP for Rochdale who has campaigned for a trial of facts, told the Guardian that if the report is accurate, Saunders will now have to consider her position.

“I am pleased to hear the suggestion that Janner will finally face justice: the alleged victims deserve this. The allegations against him are horrific, and we need to hear the facts before a court.

“All suggestions are that Saunders reached the wrong conclusion in April and this is not the first time she has made a major mistake, She has struggled in some of her decisions to pursue journalists through the courts, too. Her job is all about judgment,” he said.

The peer’s family have insisted that Janner is innocent of all wrongdoing.

A Leicestershire police investigation into Janner interviewed dozens of alleged victims who claimed they had been abused by Janner in the 70s and 80s. The CPS concluded there was enough evidence to prosecute him for 22 offences against nine people.

However, in April, Saunders ruled that Janner, 86, should not be prosecuted on health grounds. Four doctors – two from the CPS and two appointed by representatives of Janner’s family – concluded that he is suffering from advanced dementia.

Her decision was criticised after it emerged that several other alleged paedophiles who have been diagnosed with dementia have still been pursued through the courts, and a review of the decision was announced last month.

Janner, the former MP for Leicester West, was not interviewed during the latest police investigation, Operation Enamel, because of poor health but police obtained warrants to search his home in Golders Green, north London, and his office in the House of Lords.

In her statement in April, Saunders said there was enough evidence to charge Janner with 14 indecent assaults on a male under 16 between 1969 and 1988; two indecent assaults between 1984 and 1988; four counts of buggery of a male under 16 between 1972 and 1987; and two counts of buggery between 1977 and 1988; but the evidence from four medical experts on Janner’s dementia meant it was not in the public interest to charge him.

It is understood that the barrister who reviewed the CPS file cannot make a decision to launch a “trial of facts”, but can make recommendations which the CPS is likely to accept.

A spokesman for the CPS said: “The victims’ right to review is not complete until a decision has been taken by the CPS on the basis of advice received. It is important that efforts are made to inform the victims in this case of the decision once it has been made. We will of course make that decision public too.”