long-serving Labour MP was on Thursday suspended by the party following multiple claims of inappropriate behaviour towards junior colleagues.
Geraint Davies, 63, has been administratively suspended from the party and will sit as an independent while an investigation takes place.
It follows allegations reported by Politico that the Swansea West MP harassed young female staff.
Five women, including two female MPs, claimed he subjected them to unwanted sexual attention or made improper comments during incidents on the parliamentary estate.
One Labour Party activist told the news website, which spoke to 20 people who worked with Mr Davies in parliament, that she was 19 years old when he singled her out for private chats outside work hours.
Mr Davies said he does not “recognise” the allegations and apologised if he “inadvertently caused offence to anyone”.
It is understood no formal complaints about his behaviour have been made to Labour Party authorities.
Mr Davies, a former Croydon Council leader, was first elected as MP for Croydon Central in 1997. He lost the seat to the Tories in 2005, but was elected as Labour MP for Swansea West in 2010.
A Labour Party spokesman said: “These are incredibly serious allegations of completely unacceptable behaviour.
“We strongly encourage anyone with a complaint to come forward to the Labour party’s investigation.
“Any complainant will have access to an independent support service who provide confidential and independent guidance and advice from external experts throughout the process.”
The Evening Standard has contacted Mr Davies for comment.