The Independent Inquiry into Child Sexual Abuse (IICSA) has said in a new report that police officers shut down investigations into the former MP Lord Janner "without pursuing all inquiries".

The inquiry also criticised the police over a "a series of failings" when investigating allegations of child abuse against the late Lord Janner.

However, Daniel Janner QC, who has long argued that the inquiry has been a “witch-hunt” against his father, told the JC: "Our late father’s innocence is unchallenged in this report.

"It offers no proof whatsoever of guilt. He was himself the victim of institutional failings because he was denied the ability (in court) while of sound mind prior to his dementia to defend himself and challenge the false allegations.

"The fact that all the civil claims made against his estate were withdrawn or discontinued speaks for itself."

But Professor Alexis Jay, chairman of the IICSA inquiry, said police and prosecutors appeared reluctant to fully investigate claims against Lord Janner despite “numerous serious allegations".

She said: "On multiple occasions police put too little emphasis on looking for supporting evidence and shut down investigations without pursuing all outstanding enquiries.

"This inquiry has brought up themes we are now extremely familiar with, such as deference to powerful individuals, the barriers to reporting faced by children and the need for institutions to have clear policies and procedures setting out how to respond to allegations of child sexual abuse."

The inquiry, which was set up to examine whether public institutions had failed to investigate child abuse, heard accounts from 33 complainants, with allegations of abuse stretching across three decades.

Lord Janner died in 2015, suffering from acute dementia, but the IICSA decided to treat allegations against him as a separate strand of its overall inquiry.

In 1999, Leicestershire Police's Operation Magnolia looked into allegations made against the politician.

The IICSA report found that the Leicestershire investigation was "insufficient" and seemingly involved a "deliberate decision" to withhold key witness statements from the Crown Prosecution Service (CPS).

The IICSA  inquiry also said in relation to the same 1999 probe that there was "no evidence" that police were "unduly influenced or placed under improper pressure not to pursue the Lord Janner allegations".

A CPS spokesman said about the latest IICSA  findings: "The CPS has acknowledged past failings in the way allegations made against Lord Janner were handled.

"It remains a matter of sincere regret that opportunities were missed to put these allegations before a jury.

"We have co-operated fully with the inquiry and will carefully consider its conclusions."

Simon Cole, the Chief Constable of Leicestershire Police, said: "On behalf of Leicestershire Police, firstly, I would like to reiterate the wholehearted apology I gave in February 2020 to any complainant whose allegations during earlier police investigations into Lord Janner were not responded to as they should have been.

"It is fair and correct to say that the allegations could and should have been investigated more thoroughly, and Lord Janner could and should have faced prosecution earlier than 2015."