Those contacted by Ms. Lee, the notice cautioned, should be “mindful of her affiliation with the Chinese state and remit to advance the C.C.P.’ s agenda in U.K. politics.”
Efforts to reach Ms. Lee on Thursday were unsuccessful.
“I know it will be deeply concerning to many that an individual who has knowingly engaged in political interference activities on behalf of the Chinese Communist Party has targeted” lawmakers, Priti Patel, Britain’s home secretary, said in a statement.
Nevertheless, she added, the revelation was a sign of the structures Britain had in place to identify foreign interference or any potential threats to democracy.
Iain Duncan Smith, a Conservative lawmaker who has been sanctioned by China, said that the presence in British politics of an active agent of the Chinese government was “a matter of grave concern,” adding that it put people seeking refuge in Britain from the Chinese Communist Party at risk.
Tom Tugendhat, a leading voice on foreign policy in Parliament, said on Twitter that the current case illustrated the need to maintain vigilance against foreign interference.
“It is clear that the challenge from Beijing is increasing, and we need to defend our democracy against hostile activity,” said Mr. Tugendhat, who is the chairman of the Foreign Affairs Select committee.