Mr Gardiner had been a Labour minister in Sir Tony Blair’s government. He was later promoted to Jeremy Corbyn’s shadow cabinet and stood to take up a position of prominence in power should Mr Corbyn have won either of two elections that he lost. 

In a statement, a spokesman for the Chinese Embassy in London denied MI5’s claims, inisting China always adhered to the principle of non-interference in other country’s internal affairs.

“We have no need and never seek to ‘buy influence’ in any foreign parliament. We firmly oppose the trick of smearing and intimidation against the Chinese community in the UK,” it said.

Barry Gardiner ‘introduced Tory MP to spy’

A former Conservative MP employed as a consultant by Ms Lee’s law firm said on Friday that he was introduced to her by Mr Gardiner. 

Neil Carmichael, who represented Stroud between 2010 and 2017, lists himself as the chief education consultant at Christine Lee & Co on his website. He is also the chief executive of UK-China Culture and Education Co-operation Promotion Centre Ltd, which is registered at the address of Ms Lee’s law firm, and classes Ms Lee as vice chairman.

Mr Carmichael said that his direct work with the law firm was limited, adding: “In the House of Commons, I initially met her [Ms Lee] via Barry Gardiner, who introduced me to give a talk to some Chinese students. The allegations have come as a complete surprise, my work has been around education and marketing, not politics.”

Sam Armstrong, the director of communications at the Henry Jackson Society, said: “While there is little evidence that it was successful, Christine Lee’s activities look a lot like a bad version of The Manchurian Candidate. The political parties involved must now probe whether these individuals — very well unwittingly — have been exploited by a communist state.”