The accusation from China came a few weeks after Britain charged three men with assisting Hong Kong’s intelligence service.

Britain’s Secret Intelligence Service, or MI6, building in London. The accusations by China are the latest in a series of back-and-forth espionage claims between the countries.Credit…Jan Woitas/dpa, via Reuters Connect

China’s top security ministry accused Britain’s MI6 intelligence agency on Monday of persuading a married couple working for unnamed central Chinese government bodies to become spies for the British government, the latest in a volley of continuing espionage accusations between the two countries.

In a post on its official WeChat account, China’s Ministry of State Security said MI6 British intelligence officials had lured a man with the surname Wang, who worked for a Chinese government agency with part-time consulting work that paid him a high salary during his visit to Britain as part of an exchange program.

The Chinese ministry said MI6 trained Mr. Wang to become a spy and ordered him to return to China to gather intelligence. It said that his wife, who has the surname Zhou, also agreed to spy for Britain. China said the matter was under further investigation, but it is not clear whether the couple are being detained by the Chinese authorities.

This is the latest in a series of back-and-forth espionage accusations between Beijing and London, a source of escalating tension between the two countries.

Last month, three men in Britain were charged with gathering intelligence for Hong Kong, a former British colony now under Chinese rule, to pursue pro-democracy activists living in Britain.

China has condemned these latest accusations. It said that Britain had leveled a series of “groundless and slanderous” accusations of spying and cyberattacks against Beijing.

In March, the British government accused China of cyberattacks that compromised the voting records of tens of millions of people. It also charged two men, who were arrested last year, with spying for China. One of the men worked as a researcher in Parliament alongside prominent lawmakers, on China policy.

In this latest accusation of espionage, China said MI6 started courting Mr. Wang in 2015 when he applied to study in Britain as part of an exchange program. It said that MI6 took “special care of him” and learned that he had “a strong desire for money.”

After overpaying him for consulting work, the British agents revealed their true intention to Mr. Wang, the Ministry of State Security said. MI6 forced Mr. Wang to lure his wife, who worked in “a core and crucial unit” of the Chinese government, into the operation and promised to pay them twice as much, China said.

For its part, Beijing has lodged its own accusations of British spying. In January, China’s State Security Ministry said it had detained the head of an overseas consulting agency for working as a spy for the British government to collect state secrets. The agency said that British intelligence had recruited and trained the individual, who is from an unspecified “third country” in the United Kingdom and other places. This person provided the British government with 14 state secrets, the ministry said.

These accusations are hard to verify because there is little detail beyond the morsels of information provided by Chinese security agencies, and espionage cases are not open to the public in China.

China’s state security has become increasingly vocal about the threat of espionage through consultancy work. It has been imploring its citizens through social media posts and online comics to be vigilant about the hidden risks.

The ministry released a comic this year based on what it called an actual espionage investigation by a special state security official who went undercover to infiltrate a consulting company whose owner was an “associate” of a foreign spy. This official found evidence that this company was illegally contacting experts in sensitive industries.

Steve Tsang, director of the SOAS China Institute in London, said verifying the MI6 case, like China’s previous accusation, was close to impossible because the Chinese reveal only a minimal amount of detail and British intelligence was unlikely to confirm or deny the allegation.

He noted that tension between China and Britain was “higher than it has been for a while,” especially after the recent arrests. Mr. Tsang said it was not clear whether this was retribution or just more of China’s recent “paranoia” about foreign espionage.

On Monday, Mao Ning, a spokeswoman at China’s Ministry of Foreign Affairs, said she had no additional information about the case. A Downing Street spokesman declined to comment on China’s claims.