A Russian woman working in the British parliament is to be deported after security services arrested her on suspicion of espionage, the Sunday Times reported.

Britain's domestic intelligence service MI5 decided that Katia Zatuliveter, 25, who works for Mike Hancock, a Liberal Democrat member of the House of Commons defence select committee, was secretly working for the Russian intelligence service as a 'sleeper', the paper reported.

The arrest 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 Russia.

The newspaper said MI5 believes Ms Zatuliveter was deliberately targeting Mr Hancock, who has a strong interest in Russia.

The 64-year-old dismissed allegations that his assistant was a spy.

'She is not a Russian spy. I know nothing about espionage, but she has been subjected to a deportation order. She is appealing it, because she feels - quite rightly - that she has done nothing wrong,' he told the Press Association.

A spokesman for the Home Office, or interior ministry, said: 'We do not routinely comment on individual cases.'

Mr Zatuliveter, who underwent security vetting before taking up her job, was arrested by police and immigration officials last week and is being held at a secure facility awaiting deportation to Russia.

The move to deport her comes after she was stopped while re-entering Britain at London's Gatwick airport in August. Before releasing her, security officials questioned her in depth about her work for Mr Hancock, the report said.

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.'

The report said the lawmaker employed Zatuliveter after meeting her in Strasbourg, where he often travels on business as a member of the parliamentary forum of the Council of Europe.

The deportation could place further strain on Britain's diplomatic relations with Russia, which are only just emerging from an icy period after the murder by poisoning of the dissident Russian spy Alexander Litvinenko in London in 2006.