Video report by ITV News Political Correspondent Libby Weiner
Some House of Commons staffers are subjected to horrendous sexual abuse that involved groping, pawing and stroking, a damning report into bullying by MPs has revealed.
Gemma White QC said there was a "significant problem" about the way some MPs treated those who worked for them.
"Some staff of Members of Parliament are subject to an unacceptable risk of bullying and harassment, including sexual harassment, at work," she said.
Some MPs were accused of physical abuse, with some described as "unwelcome sexual advances, often accompanied by attempts at kissing".
Ms White reported: "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."
Mel Stride, leader of the House, said it was incumbent upon MPs to raise standards after the report highlighted "deeply unsatisfactory" behaviour.
"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," she added.
"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'.
"They also often have strong party and personal loyalties which constitute significant barriers to complaint."
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 said: "Working in the Houses of Parliament is meant to be an honour, but the actions of some MPs and staff members destroys any sense of pride.
"We are expendable staffers, with no independent HR service, and therefore no recourse."
House of Commons speaker John Bercow has faced calls to quit over allegations that he bullied two members of his staff.
But he responded by calling for an independent inquiry into the culture in the Commons, which was ordered by then leader of the House, Andrea Leadsom.
In response to the report, the House of Commons Commission - which is responsible for the administration of the Commons - said it condemned any bullying and "takes very seriously its responsibility to ensure that Parliament is a modern workplace".
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.
And Speaker Bercow added: “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."
A 'drip, drip' of abuse - and evidence of sexual advances
The report said the most common form of bullying was MPs who "shout at, demean, belittle and humiliate their staff on a regular basis, often in public".
Ms White wrote: "The constant 'drip, drip', as more than one contributor put it, eats away at the employee's self-confidence until they become anxious, exhausted and ill, incapable of performing their job and - often following a period of sick leave - resign or are dismissed.
"Well over half of the people who contributed to this inquiry described suffering significant mental and/or physical illness as a result of this type of bullying behaviour.
"Sexual harassment is also a problem, with staff being subject to unwanted sexual advances, often accompanied by touching, sometimes forceful."
She added that were was an unacceptable level of sexual 'banter' and unwelcome discussion of intimate sexual details.
"Some of the worst offenders are well known as such within the Parliamentary community but, other than the odd 'quiet word' from a fellow MP or the relevant whips office, action has rarely been taken to address their behaviour," she said.
"In the words of one contributor, there has been a 'general disregard for the dignity, wellbeing and employment rights of MPs' staff'."