China's ambassador to London has told Britain that it will suffer "setbacks" in its relationship with Beijing if it continues to raise issues about human rights.
The warning came after a junior Foreign Office minister took Beijing to task at a Chinese embassy function on Monday, held to mark the 71st anniversary of the People's Republic.
In his remarks, James Duddridge said that while Britain wanted to retain good relations with China, it was also concerned about Beijing's erosion of democracy in Hong Kong and its treatment of the Muslim Uighur minority in Xinjiang.
Mr Duddridge’s comments drew a cool response from Liu Xiaoming, the Chinese ambassador, who is understood to have replied pointedly that as Hong Kong was no longer under British rule, Beijing was not obliged to listen to British concerns.
Mr Liu added that China's policies in Xinjiang, where the government has been accused of putting up to two million people into "re-education" camps, were designed to combat terrorism.
Unless Britain and China observed a policy of "non-interference" in each other's internal politics, he continued, their relationship "would suffer setbacks or even retrogression."
Mr Liu, 64, who has been China's envoy to London since 2010, is one of a new generation of Chinese diplomats who have eschewed the low profile traditionally favoured by their predecessors. Earlier this year, he hinted that some Chinese companies might pull out of Britain after the government reversed its decision to allow telecoms giant Huawei a key role in the 5G network.
Last year, he also criticised the then Foreign Secretary, Jeremy Hunt, over his support for pro-democracy demonstrators in Hong Kong, saying the protests were "a matter about breaking laws".
His robust reply to Mr Duddridge's comments, which were made during an online gathering of guests, will be seen as a further indication of how relations between London and Beijing have cooled. Traditionally, routine diplomatic functions are not seen as forums where political differences are aired.
Other Chinese ambassadors have already taken up a much more aggressive tack than Mr Liu, developing what become known as "wolf-warrior" diplomacy - a new, assertive dialogue to remind the world that China is now a superpower.
Named after a Chinese film in which Beijing's troops defeat US enemies in Africa and Asia, the "wolf warrior" tactic was pioneered by Zhao Lijian, until last year China's envoy to Pakistan.
In July last year, he got in a vicious Twitter spat with Susan Rice, a former advisor to Barack Obama, about China's treatment of Uighur Muslims, in which he suggested America improve its own record on race relations. It culminated in Ms Rice urging the Chinese government to recall him to Beijing.