Britain's MI5 security service warned the ruling Conservative party that two would-be MPs could be Chinese spies, a Minister said on Wednesday.
Details of the advice, given in 2021 and 2022, comes days after it emerged a parliamentary researcher was arrested in March on suspicion of spying for Beijing.
Junior Health Minister Maria Caulfield said her party acted promptly to drop the two potential candidates for Parliament after MI5's intervention.
"I think whichever party is in government, there will always be those who are trying to target it, either to get information or to influence," she told Times Radio.
In the case of the two possible candidates "who the Conservative Party were warned about, swift action was taken and they were removed from the list," she added.
"They are not standing for election."
Caulfield was speaking after a report in The Times daily said MI5 raised concerns that the pair had links to the Chinese Communist Party's United Front Work Department, a body charged with influencing global policy and opinion.
"It was made very clear that they posed a risk," the report quoted an unnamed source as saying.
"They were subsequently blocked from the candidates list. They weren't told why."
Prime Minister Rishi Sunak's government is under pressure to toughen its policy on China as it seeks greater engagement with the Asian superpower.
When he was running for the Conservative party leadership last year, Sunak called China the "number one threat" to domestic and global security.
But in power he has rowed back on that tough rhetoric, instead characterising China's rise as a strategic challenge and pushing for pragmatic engagement to tackle issues such as climate change.
The spying suspect arrested in March issued a strong denial Monday stating that he was "completely innocent".
Another man was also arrested at the time, also on suspicion of offences under the Official Secrets Act.
Both men were released on bail pending further inquiries until October.
Chinese Foreign Ministry spokeswoman Mao Ning told a Beijing news conference on Monday that "the so-called claim that China is conducting espionage activities against the UK is pure fabrication.
"China resolutely opposes this," she added.
