A Hampshire 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.

Mr Hancock 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.

A former Hampshire county councillor he lives inFareham and is the MP for Portsmouth South.

Describing Ms Zatuliveter as ''bright and intelligent''.

Mr Hancock said: ''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.''

It was reported today 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 said: ''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 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.

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.''