Complaints that MPs bullied, harassed and intimidated House of Commons staff have been uncovered in an investigation by BBC Two's Newsnight.
Female workers described aggressive and threatening behaviour, saying complaints were not taken seriously.
Among those accused of bullying was Speaker John Bercow, whose private secretary left her job in 2011.
His spokeswoman rejects the allegation he behaved in such a manner, "either eight years ago, or at any other time".
"Any suggestion to the contrary is simply untrue," he said.
The House of Commons said it did not tolerate bullying or harassment, however Lib Dem deputy leader Jo Swinson called for a "thorough, independent investigation".
Signed off sick
Newsnight has been investigating claims of bullying and harassment by MPs of members of the House of Commons Service - a group commonly known in Westminster as "clerks".
It found that women working in the House said they had been pushed against walls, forcibly kissed, groped and slapped by MPs.
They told Newsnight their complaints had not been taken seriously, and that they fear that when complaints are made it is the clerks who are made to move jobs while the MPs are left in place.
Since 2014, when the current HR processes were introduced, no complaints raised by staff members have been escalated to formal channels, such as mediation.
One of the stories that emerged was that of Kate Emms - who worked as a private secretary to Mr Bercow, starting in mid-2010.
Colleagues who spoke to Newsnight claimed that Mr Bercow, who is also the MP for Buckingham, had shouted at her and undermined her in front of other staff. This left her unable to continue working in what was a key Commons post, they said.
She was signed off sick in early 2011 and then returned to a new post elsewhere in Parliament.
Commons authorities were told that she had been suffering from post-traumatic stress disorder.
Two other MPs named in the investigation were Labour's Paul Farrelly and Conservative Mark Pritchard.
Witnesses told Newsnight that Mr Farrelly's continued criticism over several years of Emily Commander, a clerk on two committees that the MP sat on, made her job impossible.
One witness recalled his behaviour on a science committee trip to Italy in 2004, saying: "He was a complete and utter bully.
"He wound her up like a screw and reduced her to tears. The more he upset her, the more he enjoyed it, the more he kept turning the screw. He was very aggressive. It felt like no one had the ability or authority to intervene. Everybody knew it was wrong."
The two crossed paths again when Mr Farrelly was on the culture, media and sport committee in 2010.
Documents obtained by Newsnight show she complained then of a campaign of continual belittling and undermining and that she told her bosses that she had "repeated nightmares about going on Committee visits with Mr Farrelly and being criticised by him for having neglected tiny details".
Newsnight also spoke to several clerks about Mr Pritchard, MP for the Wrekin, who say he was notorious for shouting at and berating clerks.
One witness told how he "exploded" at a female staff member ahead of a trip to California because he was unhappy with the choice of hotel he had been booked into. He then angrily swore at the same woman on the trip itself.
Mr Farrelly and Mr Pritchard have denied all allegations against them.
Mr Farrelly told Newsnight: "In 2012 allegations were made about me having bullied a clerk to the committee during the compilation of the phone-hacking report. These allegations were investigated and not upheld."
"Despite this, I apologised if I had inadvertently upset the clerk who had suffered stress. The policy under which they were investigated was considered to be so unfair to those complained about that it was immediately withdrawn and replaced by another policy."
Mr Pritchard said: "I understand, over the past several years the House authorities have addressed numerous complaints about MPs, but they have also informed me they have no record of any complaints against me, and if they had, I would have been notified."
Writing on Twitter, Labour MP Jess Phillips, said Commons staff had told her of similar experiences and the claims "must be investigated, independently and fairly".
I met with clerks and house staff today and talked to them about they way they get treated, this was reflected in tonights piece. This must be investigated, independently and fairly. https://t.co/88WrJrGBSK— Jess Phillips (@jessphillips) March 8, 2018
Lib Dem deputy leader Jo Swinson also called for the allegations to be thoroughly investigated.
She told Newsnight the claims raised "very significant questions" about the Respect policy, which was designed to prevent bullying and harassment by MPs and their staff.
Ms Swinson, a member of the cross-party working group on an independent complaints and grievance policy, said the suggestion was Parliament "doesn't have modern and professional standards... [and] many MPs see themselves as above other members of staff".
The House of Commons said in a statement: "The House of Commons takes pride in being a responsible and supportive employer, and does not tolerate bullying or harassment of any kind."
It added the House had introduced the revised Respect policy in 2014, which aimed to combat bullying and harassment by MPs or their staff.
The House said several measures had been put in place alongside the policy including training managers on how to address reports of bullying or harassment and a team of trained contacts for staff to approach if they have concerns.
A longer version of this story is available here.