Image copyright PA Image caption Prof Jay, the fourth chair, apologised for any anxiety caused to the survivors and victims over the past few months

Heads of the inquiry into child sexual abuse have been criticised by MPs for a "wholly inadequate" response to an internal allegation of sexual assault.

The home affairs select committee said, given the inquiry's task, it should have treated the issue with "rigour".

A woman on the inquiry team alleged she was groped in a lift at its offices.

Inquiry chair Prof Alexis Jay, the fourth person to lead the inquiry, apologised for any unnecessary anxiety caused to victims or survivors.

The troubled inquiry, launched by Theresa May when she was home secretary, has seen the departure of three chairs as well as its most senior and second-ranking counsel.

In the latest setback, one of the largest victims' groups involved withdrew from the inquiry, calling it an "unpalatable circus".

The move prompted calls for Prof Jay, who has the government's backing, to be replaced.

Image copyright PA Image caption Ben Emmerson QC quit in September

Ben Emmerson QC, the most senior lawyer at the inquiry, resigned in September.

The BBC's Newsnight programme has previously reported that the inquiry was told in September of a claim that Mr Emmerson had assaulted a woman working at its offices in a lift - a claim he has strenuously denied.

The alleged victim did not want the incident investigated.

In its report, the committee said it made no judgement on the claim, and suggested an external person could be appointed to examine the matter.

"We are not in a position, and it is certainly not our responsibility, to assess either the facts of the case or the details of the processes that the inquiry pursued," the report said.

"However, we do not believe that IICSA [the inquiry] has taken seriously enough its responsibility to pursue allegations of bullying or disclosures of sexual assault within the inquiry," it added.

"Nor do we believe it has done enough to demonstrate publicly that it has a robust approach to such matters."

'Urgent action needed'

In a letter published by the committee alongside its report, Hugh Davies QC, a barrister who worked for the inquiry until December last year, said as a body judging how institutions dealt with this sort of allegation, it should "expect to be judged by the same standards it will doubtless set for others".

Labour MP Yvette Cooper, chair of the select committee, said the inquiry needed to sort out its problems fast and be less defensive about what had gone wrong.

Image copyright PA Image caption Dame Lowell Goddard says she will not give oral evidence to the Home Affairs Committee

She said it was "shameful" that the previous chair, Dame Lowell Goddard, was refusing to give oral evidence about her sudden resignation this summer.

The New Zealand high court judge previously told the committee that for her to be summoned would compromise the inquiry's "independence and integrity".

MPs also urged the inquiry team to appoint new lawyers as soon as possible and suggested it split its workload into two strands - legal matters and child protection.

Ms Cooper said: "We found there was an unresolved tension over how far the inquiry should focus on uncovering the truth about past abuse and cover-ups and how far it should focus on current child protection policies.

"Both are important but they need different skills, experience and styles of work.

"This inquiry is far too important to be sunk by problems. That's why urgent action is needed to sort them out. Survivors of abuse deserve nothing less."

'Personally sorry'

In response, Prof Jay said an external senior legal figure would be invited to review some of the issues raised in the committee's report.

"While I am confident that our safeguarding and dignity at work procedures are robust, I recognise the impact of recent speculation and commentary about them," she said.

"Nobody is more determined to deliver a successful inquiry on behalf of victims, survivors and the wider public than the panel and myself.

"We recognise that the past few months have been difficult for the inquiry and for the victims and survivors who have placed their trust in it.

"I am personally sorry for any unnecessary anxiety the inquiry may have caused to victims and survivors during this transitional period."

She is expected to publish a review of how the inquiry operates in the coming weeks.