A Russian working as a parliamentary aide to a British MP has been taken into custody to face deportation proceedings amid claims she is a spy.

According to the Sunday Times, Katia Zatuliveter, 24, was arrested on the orders of MI5 over espionage claims.

She has been working for Lib Dem MP Mike Hancock, who said she had done nothing wrong and would appeal.

The Home Office said it did not routinely comment on individual cases, nor would it confirm deportation moves.

But a security source is said to have told the Sunday Times that Ms Zatuliveter's presence was not "conducive to national security", and the intention was to "show her the door".

It doesn't surprise me at all if this is true but it does seem very strange that she was picked up sometime ago and that she was vetted Frank Gardner, BBC security correspondent

It is believed to be the first time since the end of the Cold War that someone working in Parliament has been accused of spying for the Russians, suggests the Sunday Times.

Mr Hancock told the BBC he was standing by Ms Zatuliveter. He said she had told him she had not seen any evidence against her.

"Nobody has shown me any evidence to support the view that she is any way a threat to the UK," he said. "If she was a threat, when they stopped her in August, they could have removed her then."

Mr Hancock said she had been arrested at 0700 GMT on Thursday and was subject to a deportation order.

"She was taken away and held in a detention centre in London, and then transferred to another detention centre where she is putting her appeal together," he said.

Media playback is unsupported on your device Media caption Lib Dem MP Mike Hancock: "I'm sure she's confident of winning an appeal"

Mr Hancock is MP for Portsmouth South, a city which has a large naval base. He also sits on the House of Commons Defence Select Committee.

Despite acknowledging that he has asked for information on the location of nuclear submarines and has probably asked more defence questions than any other MP, he said his work was not "top secret".

"There is nothing she was doing for me that was in any way sensitive," he added.

"I have never read anything in a defence select committee paper or report which was worth anyone believing they had something they could not get from another source."

Police interviews

The BBC's security correspondent Frank Gardner said Russian intelligence agencies had a "very low threshold" for information and they would frequently "try to acquire by covert means what is out there on the internet or in open publications".

Espionage here is much easier now because most of MI5's resources have to be devoted to the terrorist threat Chapman Pincher, Espionage expert

"It doesn't surprise me at all if this is true but it does seem very strange that she was picked up sometime ago and that she was vetted," he said.

Ms Zatuliveter was first stopped in the summer and had been interviewed by police four or five times since.

Our correspondent said it was possible the UK security forces knew about her activities and had been "playing her".

"To me, it strikes of a little bit of incompetence that they would vet this woman and allow her to be in a position of some sensitivity," he said.

He added that the level of Russian espionage was back up to where it was in the late 80s, and there were up to 35 Russian intelligence officers working covertly in the UK who then employ others.

The allegation comes after 10 Russian agents, including Anna Chapman who had dual Russia-UK citizenship, were expelled from the US in July.

Superpower

Author Chapman Pincher says spy games have increased because the Russian PM Vladimir Putin is determined to restore his country's status in the world.

"They were a superpower until the collapse of the Soviet Union, and he wants to get back to that position, so it's business as usual," he said.

"Espionage here is much easier now because most of MI5's resources have to be devoted to the terrorist threat."

He said the Russians recruited anyone, regardless of their age, who was able to get into a position of trust.

"They take a very long-term view - let's get someone in there even if we aren't sure what he or she will get," he added.

Ms Zatuliveter started working as an assistant to Mr Hancock in 2008. She had previously been an intern at the House of Commons and had worked in Europe.

Work and Pensions Secretary Iain Duncan Smith told Sky News it was a cause for concern and that "you have to take it quite seriously".

Shadow Foreign Secretary Yvette Cooper told the BBC's Andrew Marr Show that vetting procedures for those applying to work in the Commons might have to be re-examined.