Katia Zatuliveter, a researcher for an MP on the influential defence select committee, is to be expelled from Britain after being questioned on suspicion of espionage by security services.

Mr Hancock has recently asked sensitive questions in Parliament about the quantities of radioactive materials held by the country and the future of its nuclear deterrent.

Miss Zatuliveter has also worked for a defence think-tank and written articles that criticised Nato while defending military action by Russia.