An MP said today he backed his researcher 100%, saying she had "nothing to hide" after she was arrested on suspicion of being a Russian spy.
Liberal Democrat Mike Hancock challenged the security services to produce evidence against Katia Zatuliveter, 25, who faces deportation after being arrested on Thursday morning.
She came to the UK three years ago to study for a masters degree at Bradford University before starting work as a researcher in Mr Hancock's parliamentary office in the House of Commons.
He is a member of the Defence Select Committee but denied she would have been privy to any secret information that was not available to the public.
Describing Ms Zatuliveter as "bright and intelligent", Mr Hancock told Sky News: "I have no reason to believe she did any thing but act honourably during the time she was working for me.
"She is determined to fight her corner and she genuinely believes, and I back her 100%, that she has nothing to hide and has done nothing wrong. If she has, the (security) services are right. But they need to prove their point now."
The Sunday Times reported that Home Secretary Theresa May had approved the removal of Ms Zatuliveter after being briefed by MI5 about her alleged connection to Russia's foreign intelligence service, the SVR.
She held a House of Commons pass and underwent security vetting before taking up her position and is currently being held at an immigration detention centre as she puts together an appeal against deportation.
A source told The Sunday Times: "Her presence here is not considered to be conducive to national security. There was unhappiness about what she could have access to. The intention is to show her the door."
If confirmed, this would be the first case since the Cold War of a Russian agent being removed from the Houses of Parliament.
Mr Hancock said the first he knew about Ms Zatuliveter's arrest was on Thursday lunchtime when he received a telephone call to say she had been detained. The Portsmouth South MP said he hoped she would be at work as he was unable to make it to the House of Commons because he was snowed in.
In an interview with the BBC, he said she had first worked as an intern in his office before she started working full time as a researcher two and a half years ago. He said she had been interviewed by the security services in August, after she was stopped as she returned to the UK from holiday. She had a tier one visa, which are reserved for highly skilled workers.
He said: "Nobody has shown me any evidence to support the view that she is in any way a threat to the United Kingdom.
"I am surprised. I haven't seen anything, and they (the security services) haven't contacted me recently and they didn't give me any warning she was going to be detained. She has a perfect right to appeal and I am sure she is confident of winning the appeal."
He added: "As far as I am concerned there was nothing she was doing for me that was sensitive. Defence Select Committee papers have been leaked to newspapers before now and I have never read anything in a Defence Select Committee paper or report which was worth someone believing they couldn't get from another source."
Mr Hancock said his researcher's role included hosting constituents during visits to the Houses of Parliament, writing speeches and working on tabling early day motions. She was currently researching a report about the problem of obesity, he said.
He said: "Katia was ambitious, she had ideas to go a lot further than just working for an MP in the House of Commons. I think she would be the last to be involved in that (spying). Given the part of Russia she comes from and her background, that would have been the last thing that would have entered her head."
In a statement, he added: "In light of all these circumstances, it is difficult to understand the reasons for all this. She has been an excellent and conscientious employee and I wish her well in all this."
MPs today voiced their concerns about the fact Ms Zatuliveter was handed a parliamentary pass.
Shadow foreign secretary Yvette Cooper said that the Zatuliveter case might require a review of security in Parliament.
Ms Cooper told BBC1's Andrew Marr Show that she did not know anything about the individual case of the Russian researcher.
But she added: "There are parliamentary security checks on anyone who applies for a House of Commons pass, anybody who is going to work in the House of Commons. Of course it is important to make sure that these are strong enough and secure enough.
"Depending on what happens in this individual case, if there do turn out to be problems and breaches of security here, then obviously the wider security in Parliament would need to be looked at, and I am sure the Speaker would take that very seriously."
Work and Pensions Secretary Iain Duncan Smith told Sky News' Sunday Live with Adam Boulton: "I have never seen or met her and the trouble is I would say normally this would be a joke but actually after what's been going on with some of the spies that Russia seems to have put into all sorts of places, you have to take it quite seriously really I suppose."
Shadow communities secretary Caroline Flint said the case resembled a storyline out of Spooks.
She told Adam Boulton: "You have to be careful about these things in terms who gets these passes. You have to go through proper security checks, and as far as I am aware from my own staff, you put in an application and then various checks are made before someone gets their pass.
"I am sure they will be looking at the pass for this individual but we don't know the details and we will have to look at what comes out of it."
Asked about the report, a Home Office spokesman said only: "We do not routinely comment on individual cases."
It was not immediately possible to contact Ms Zatuliveter or her lawyers.
Referring to the deportation of ten Russian sleeper cells from the US in July, Kim Howells, the former Labour MP who chaired the House of Commons Intelligence and Security Committee, said it was the job of spies to infiltrate policy-making circles and report back to their handlers in Moscow details such as public opinion.
He said the Russians would have been very interested in finding out details about the large naval base in Mr Hancock's constituency, telling Radio 4's The World this Weekend there needed to be much sharper vetting of parliamentary assistants.
"The last time this kind of thing came up was when one MP or maybe more were actually hiring people who had links to the IRA.
"That was a very long time ago now and I trust the security of the Palace of Westminster hasn't slumped in that time and that people are as sharp as they ought to be about infiltration.
"The murder of Alexander Litvinenko who had been a Russian spy but became a dissident, he was certainly killed by Russian agents back in 2006. They want their tentacles to be able to reach anybody they consider to be a danger to the Russian state, even if it means killing them on the streets of London.
"I think the Foreign Office and intelligence services are acutely aware of this threat and I think they are going to be looking at making more funding available for the security services to tackle this kind of threat. I hope they are anyway."
In an interview with Channel 4 News, former Russian spy Oleg Gordievsky who defected to the UK in 1985, said the FSB (formerly the KGB), said: "Russians are spying just as much as before, only now it's easier because Russians believe that the Western public is very, very easy.
"All bits of military information are of great importance to the FSB. And she would have very easy access to it and lots of other information at the MoD. They use that information to make foreign policy decisions."Reuse content