A probe into sexual intimidation and harassment at Westminster has found that MPs’ staff face an “unacceptable risk” of abuse.

The hard-hitting independent investigation heard that some people who work for MPs have to cope with “very serious sexual assault” and having heavy objects thrown at them in bouts of “uncontrollable rage”.

Gemma White QC said there was a “significant problem” about the way some MPs treated those who worked for them.

She said the House of Commons authorities had been too slow to act in response to previous reports into the issue.

“Some staff of Members of Parliament are subject to an unacceptable risk of bullying and harassment, including sexual harassment, at work,” she said.

“Most Members of Parliament treat their staff with dignity and respect but the problem of bullying and harassment is sufficiently widespread to require an urgent collective response.

“Recent steps taken by the House of Commons to address bullying and harassment across the Parliamentary community do not engage sufficiently with the particular issues faced by members’ staff, who are in a uniquely vulnerable position because they are directly employed by Members of Parliament.

“Many describe the idea of complaining about bullying and harassment under the new complaints procedure as ‘career suicide’.”

The probe heard that staff working for MPs have been subjected to “very serious sexual assault”.

Ms White said: “The behaviour described to me ranged from ‘jokes’ regarded by those making them – and in one case the MP to whom the member of staff complained – as acceptable workplace banter, all the way through to conduct which can only be described as very serious sexual assault.”

She added: “Many of the experiences related to me were of unwelcome sexual advances, often accompanied by attempts at kissing.

“Many involved some form of unwanted touching: for example breasts being grabbed, buttocks being slapped, thighs being stroked and crotches being pressed/rubbed against bodies.”

Ms White said “Contributors reported being shouted at and/or sworn at by their MP employer on a regular basis.

“Some contributors described members expressing uncontrollable rage, screaming that staff were ‘f***ing useless” or “f***ing idiots’ in front of other staff, other members and/or constituents.

“Some contributors who reported shouting and screaming also told of being present when objects – usually pieces of office equipment, sometimes heavy – were thrown in anger by their employer MP, in some cases at them.”

One staff member told the investigation: “As long as getting political jobs in Parliament are dependent on who you know and who you’re related to, sexual harassment will be a necessary evil for ambitious young… people like me who will choose our careers over our comfort every time.”

Another employee said: “When the MP requests that the researcher should vacuum clean and dust the member’s flat ahead of a private party, a line has been crossed.”

Commons Leader Mel Stride told MPs there will be a “general debate” on the report followed by a “debate on a motion relating to the changes to the Independent Complaints and Grievance Scheme (ICGS)” next week.

This could see MPs backing the report’s call for historic claims of abuse to be considered under the ICGS as at present only those relating to the period since the last general election in June 2017 can be dealt with.

It is understood that historic grievance claims could run into the thousands.

Mr Stride said: “Any one person – and I say this as a father of three daughters – who is put into a position where they are preyed upon by somebody in authority, that is one way too many.

“And that needs to be stamped out.”

It is understood some 300 people contacted the ICGS with complaints in the three months to June 2019.

Downing Street described Ms White’s report as “deeply worrying”.

“The findings in this report are appalling and raise serious concerns,” the Prime Minister’s official spokesman said.

Commons Speaker John Bercow said: “Gemma White’s findings are deeply shocking and some of the allegations mentioned in her report should be reported to the police and action taken. It is totally unacceptable for any MP to behave in this way.

“The Speaker does not have any powers over MPs in relation to their staff. However, he believes strongly that the House should restrict the sale of alcohol on the estate, consider the introduction of CCTV in MPs’ offices and encourage all members to go on employer training courses.”

Ms White’s investigation was ordered last year by the then leader of the House, Andrea Leadsom, following a highly critical report by Dame Laura Cox which highlighted the widespread bullying and harassment of staff.

In her findings, Ms White said such behaviour had been “tolerated and accepted” for too long.

“It has seriously affected the health and welfare of far too many people,” she said.

“There is a pressing need for a collective response to what is clearly a significant problem.

“I am concerned by the amount of time it has taken to act on recommendations from previous reports and would urge the House to move more swiftly.

“While the House of Commons is not alone in tolerating these behaviours, it is the home of our policy makers and a taxpayer-funded institution. It should therefore be at the forefront of good employment practice.”