Former colonial governor Chris Patten has called on the U.K. to rethink its ties with China's ruling Communist Party, warning of further escalation of political persecution by authorities in Hong Kong.



Lord Patten of Barnes said Beijing appears to be reneging on an international, legally binding treaty governing the status of Hong Kong, which was promised the continuation of its traditional freedoms after the 1997 handover to Chinese rule.



"Beijing officials have made statements about their role in Hong Kong which are a flagrant breach of the Joint Declaration and the Basic Law," Patten wrote to U.K. foreign secretary Dominic Raab, referring to the treaty and to Hong Kong's mini-constitution respectively.



"They claim the right to call all the shots in Hong Kong thus destroying once and for all the promises that Hong Kong would have a high degree of local autonomy," he wrote in the April 26 letter.



The letter said the arrest this month of 15 pro-democracy politicians for taking part in mass, peaceful rallies last year could just be the start of escalating political control by Beijing over Hong Kong.



Patten said there are widespread concerns in Hong Kong that Beijing is getting ready to make "mass disqualifications" of pro-democracy lawmakers and candidates in September's election to the city's Legislative Council (LegCo), "or worse still cancel those elections."



He said Beijing is preparing to enact "draconian" national security legislation outlawing subversion and sedition, and to "continue with the politicised strategy of prosecution" that has seen dozens of people prosecuted for taking part in peaceful assemblies.



"There is no 'golden age' in our relations with the Chinese Communist Party," Patten wrote. "We must work with China even while it suffers under a Communist dictatorship."



"But we should do so with our eyes open and while stripping away the mendacity and the cant," the letter said, referring in particular to attempts by Chinese officials to deny there had been any attempt to cover up human-to-human transmission at the start of the coronavirus epidemic in the central city of Wuhan.



Labor Day gatherings banned



Patten's warning came as police in Hong Kong refused to give permission for a Labor Day demonstration on Friday, warning that anyone who participates in a gathering of more than four people could face up to five years in jail.



"Police have grounds to believe that the activities do not only increase the risk of infecting COVID-19 by participants and other people, but also pose serious threat to the lives and health of all citizens, jeopardizing public safety and affecting the rights of others," the police said in a statement dated April 24.



Police on Thursday fined a group of League of Social Democrats activists after they protested the ban outside police headquarters.



The activists refused to disperse after being ordered to leave by police, saying they had spaced themselves 1.5 metres apart and were divided into groups of four.



Police also used coronavirus as a reason to break up gatherings in malls at the weekend, although the city hadn't seen any new cases for five days straight by Thursday.



Reported by RFA's Cantonese Service. Translated and edited by Luisetta Mudie.