A backbench MP has been suspended by the Liberal Democrats after a report found "compelling" evidence of "serious and unwelcome sexual behaviour" towards a woman constituent.
Mike Hancock, the MP for Portsmouth South, has had his membership of the party suspended with immediate effect, a spokesman said.
The move follows the leak of an unpublished report into his conduct carried out for Portsmouth City Council - where Mr Hancock sits as a Lib Dem councillor - by Nigel Pascoe QC.
The MP voluntarily resigned the Lib Dem parliamentary whip last year to contest a High Court civil action alleging sexual impropriety and now sits at Westminster as an independent.
A Lib Dem spokesman said the party had only seen the report for the first time after a leaked copy was posted on the Guido Fawkes political website - even though details of its findings appeared in The Guardian before Christmas.
"The Liberal Democrats have this afternoon, for the first time, had sight of a Portsmouth City Council report by Nigel Pascoe QC into allegations of sexual impropriety by Mike Hancock," the spokesman said.
"Given Nigel Pascoe QC's conclusions in his report, we have immediately suspended Mike Hancock's membership of the party."
The discloure adds to the pressure on Nick Clegg who has been under fire for his handling of allegations of sexual harassment by the party's former chief executive, Lord Rennard.
In his report, Mr Pascoe said he had no doubt that the complainant had provided "compelling prima facie evidence of serious and unwelcome sexual behaviour" carried out towards her by Mr Hancock.
He described the woman as "a straightforward and vulnerable person, angry and hurt by what she said had happened to her".
He also acknowledged that Mr Hancock was not motivated "solely by sexual desire" and that he had sought to help her "wholly properly" as a local councillor.
"That said," he concluded, "I consider that the prima facie evidence of his unwelcome sexual approaches remains unquestionably a very serious matter in the light of the position which he holds and his knowledge from the beginning of the vulnerability of (the complainant).
"No one in public life should allow themselves to act in such an irresponsible and damaging way."
Mr Pascoe completed his report last August, but the council has postponed its inquiry until the court action is over.
In a statement posted on the MP's website, a spokesman for Mr Hancock said that he had not yet given evidence to Mr Pascoe and that his report was therefore likely to be "one-sided".
"These matters have twice been looked at by the police, first in 2010, and in conjunction with the Crown Prosecution Service, they have found that there is no case for Mr Hancock to answer and have taken no further action," the spokesman said.
"Portsmouth standards sub-committee has yet to meet to hear evidence including from Mike Hancock as it decided to postpone that hearing until after the associated civil court case.
"Unfortunately due to the ongoing civil case, Mike received legal advice that he should not give evidence to the council's investigator. He looks forward to giving his evidence when the sub-committee meets after the conclusion of the civil case."
Mr Hancock has always denied the accusations and says that he will vigorously contest the civil case now being brought by the complainant.
The MP has been accused of making repeated physical sexual advances towards the woman, a young mother who had asked for help with noisy neighbours, despite being made aware she suffered a mental health disorder and had been sexually abused as a child.
After a previous investigation by Hampshire Police found there was no case to answer, Mr Pascoe was appointed by Portsmouth City Council as an independent investigator to look into claims he had broken the council's code of conduct.