Mike Hancock, the Liberal Democrat who employed and allegedly had an affair with a women suspected of being a Russian spy has quit the Commons defence committee.
The MP for Portsmouth South said he would no longer attend the committee given the allegations made against his former aide, Katia Zatuliveter, by British security services.
In a letter to Lib Dem chief Whip Alistair Carmichael, seen by the Portsmouth News, he said: "I have made this decision to allow the select committee to continue with its work unimpaired by current events.
"My time serving on the defence select committee has been a real honour and I would like to pay tribute to the important work that it does and to my colleagues on the committee.
But Hancock appeared to hold out hope that he could return to the committee once the current case was concluded.
"I hope that we can revisit my membership following the conclusion of the on-going case," he said.
In reply, Carmichael thanked Hancock for his service and indicated he would be willing to see him return to his post in the future.
"As a member of the committee for more than a decade, you have contributed to its hugely important and influential work for which you are owed a great deal of thanks," he said.
"I understand your reasons for wishing to step down. I think that your concern in acting to protect the work of the select committee is exactly what I would have expected of you.
"I appreciate that this is a very difficult time for you and your family, needless to say should it ever be possible for you to return to a role of this sort, I would be keen that you should do so. "
As a member of the committee Hancock would have access to potentially sensitive information. His Portsmouth South constituency is also home to the Royal Navy.
Zatuliveter has admitted to opening select committee letters marked 'private and confidential'.
But she denies the allegation that she is a spy and has launched an appeal against the decision by the Home Office to have her deported from Britain.
At the hearing on Tuesday she admitted to having four year affair with 65-year-old Hancock. MI5 has alleged her relationship with Hancock was in part fabricated at the behest of the Russian intelligence service to allow her to spy on the MPs work.
She worked for the MP as an intern in 2006 and started working for him full time in 2008.
In a statement issued on Tuesday Hancock said: "On both occasions she was vetted by the House of Commons authorities, passed that vetting and was given a House of Commons pass. She had a valid work visa granted and renewed by the Home Office which was not opposed by the security services.
"At no time, did I pass on to Ms Zatuliveter any information that was not in the public domain or any classified information."