Katia Zatuliveter, 25, an aide to Liberal Democrat MP Mike Hancock on the influential Defense Select Committee, was arrested on Thursday and is to be deported over allegations that she was connected to the SVR, Russia's foreign intelligence service.

Britain's secret service MI5 said the assistant had access to classified documents supplied to the committee. Hancock, whose interest in Russia has been something of a concern for the House of Commons, has recently tabled parliamentary questions about Britain's nuclear deterrent and the location of its international submarine bases.

Hancock has launched a defense of the blonde researcher, saying she had "nothing to hide."

"I have no reason to believe she did anything but act honorably during the time she was working for me," he was quoted by the Daily Telegraph as saying.

"She is determined to fight her corner and she genuinely believes, and I back her 100 percent, 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," he said.

MI5 says Zatuliveter, originally from the troubled North Caucasus republic of Dagestan, met Hancock in Strasbourg where he sits on the EU Council of Europe, and then worked as an intern for him.

The Russian also worked for the British think-tank Defense Forum, where she wrote an article criticizing NATO's role in the 2008 Russia-Georgia war over South Ossetia.

She and a friend were detained at London's Gatwick Airport in August and questioned by MI5.