The Conservatives reportedly dropped two potential candidates to become MPs after MI5 warned that they could be spies for China.
The security service contacted the Tories last year and in 2021 advising the pair should not be included on the central list of candidates, according to The Times.
The newspaper reported the pair had linked to the United Front Work Department (UFWD) – China’s main agency for shaping public opinion.
It cited an unnamed source as saying: “It was made very clear that they posed a risk.
“They were subsequently blocked from the candidates list. They weren’t told why.”
A Conservative Party spokesman said: “When we receive credible information regarding security concerns over potential candidates we act upon them.”
The news comes in the wake of a parliamentary researcher arrested over allegations of spying for Beijing.
The researcher, who is in his 20s, is understood to have had links to security minister Tom Tugendhat, Foreign Affairs Committee chairwoman Alicia Kearns and other senior Tory MPs.
In a statement released by his lawyers, the man – who they did not name – said he was “completely innocent” saying he spent his career “trying to educate others about the challenge and threats presented by the Chinese Communist Party”.
The man was arrested in Edinburgh on 13 March, Scotland Yard said.
The Sunday Times revealed that another man, who is in his 30s, was also arrested in Oxfordshire on the same day.
Both were held on suspicion of offences under Section 1 of the Official Secrets Act 1911, which punishes offences that are said to be “prejudicial to the safety or interests of the state”.
On Monday afternoon, Commons Speaker Sir Lindsay Hoyle reassured MPs that the House “follows the same vetting procedures as the government” and parliamentary security “is working closely and effectively with other relevant authorities” – and keeping arrangements under review.
Sir Lindsay said a small number of people were briefed about the arrest “on a strictly confidential basis” – and warned members against prejudicing future prosecutions by discussing the matter in the House.
He said the pair were bailed until early in October.
Their arrests led to Rishi Sunak confronting Chinese premier Li Qiang at the G20 summit in India on Sunday over “unacceptable” interference in democracy.
The incident has also thrown a spotlight on the government’s stance towards China and raised questions about whether it should adopt a tougher approach.