Sir Lindsay Hoyle, Speaker of the Commons, and his counterpart in the House of Lords, Lord McFall, have circulated a new "espionage alert" issued by the security services.
The MI5 alert identified two LinkedIn profiles believed to be being used by the Chinese Ministry of State Security (MSS).
It states that they operate as "civilian recruitment headhunters" who target individuals working in British politics to obtain "insider information."
Writing to MPs, Sir Lindsay said that Chinese government actors are "constantly" trying to "interfere with our processes and influence the activities of Parliament."
He stated that the Chinese MSS is "actively reaching out to people in our community," and that they "seek to gather information and build long-term relationships using professional networking sites, recruitment agents, and consultants working on their behalf."
The MI5 alert states that "false individuals" approach their targets to "work as freelance consultants writing geopolitical reports."
Other aspects of the espionage described in the MI5 alert include fully paid trips to China and payment for information in cash or cryptocurrency.
Targets include "parliamentary staff, economists, think tank staff, geopolitical consultants, and people working with the government, including MPs and members of the House of Lords."
Former Conservative Party leader Sir Iain Duncan Smith said the alert shows China is adopting an "aggressive stance" that "blows away all the nonsense" about whether China poses a threat to Britain's national security.
"Why can't the government call China out for what it is, which poses a continuing threat to Britain's national security?
"It's clear to every member of the public... but somehow the government thinks it's not so clear."