Ekaterina Zatuliveter, also known as Katia, was arrested in December on suspicion of using her job in the office of legislator Mike Hancock to pass information to Russian intelligence.

She was not charged, but British authorities want to deport her as a danger to national security.

Zatuliveter denies spying and is asking the Special Immigration Appeals Commission to block her extradition. The case, expected to last nine days, is being heard by three judges and a former head of the MI5 intelligence agency.

Hancock, a Liberal Democrat member of Parliament who sits on the House of Commons Defense Committee, has said 26-year-old Zatuliveter worked as a researcher in his office for 2{ years, but was not involved in sensitive matters.

In a statement issued Tuesday, he said that ``at no time, did I pass on to Ms. Zatuliveter any information that was not in the public domain or any classified information.''

Zatuliveter said she met Hancock in Moscow in 2006 and they began an affair that continued when she moved to Britain to study. But she denied an allegation by Jonathan Glasson, a lawyer for the British government, that she had targeted Hancock because he was influential in British politics.

``I don't think that he is very influential,'' she said. ``He is a backbench MP.''

Asked why she thought Hancock would be of interest to Russian spies, she replied: ``I have no idea what would be of interest to the Russian Intelligence Service.''

Zatuliveter said she was first questioned by British intelligence officials in August 2010 when she was asked how she could afford her London apartment on a researcher's salary.

She said she replied that Hancock helped her out financially.

Hancock, 65, who is married with two children, said in his statement that it was ``not appropriate for me to make any further comments at this time on any aspect of the hearing.''

Russia's Foreign Ministry has dismissed the spying accusations as ``paranoid'' and an attempt to undermine U.K.-Russian relations.

Those relations have been chilled since the death in 2006 of Alexander Litvinenko, a former KGB officer who died after ingesting a radioactive substance. Litvinenko blamed Russian President Vladimir Putin for the poisoning.

Britain has sought to extradite the main suspect in the case, former KGB officer Andrei Lugovoi, but Russia has refused.