One is a researcher who has had links to several senior Tory MPs, including security minister Tom Tugendhat and foreign affairs committee chairwoman Alicia Kearns.
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The Briton was arrested along with another man by officers on March 13 on suspicion of spying for Beijing, it was revealed by the Sunday Times.
Mr Sunak, who has faced criticism from some senior Conservatives of seeking a relationship with a China they see as increasingly a threat, met Mr Li on the margins of the international summit on Sunday morning.
A No 10 spokesman said: “The Prime Minister met Premier Li Qiang and conveyed his significant concerns about Chinese interference in the UK’s parliamentary democracy.”