MI5 has warned that a Chinese government agent has been working in parliament “to subvert the processes”, MPs have been told.

Iain Duncan Smith told the Commons that Speaker Lindsay Hoyle has written to MPs to let them know he has been contacted by MI5 over the matter.

The MP said: “I understand that Mr Speaker has been contacted by MI5 and is now warning members of parliament that there has been an agent of the Chinese government active here in parliament working with a Member of Parliament, obviously to subvert the processes here.

“I say, as a Member of Parliament who has been sanctioned by the Chinese government, that this is a matter of grave concern.”

Labour frontbencher Barry Gardiner