BEIJING (Reuters) - China on Tuesday offered strong support to the Hong Kong government’s decision to arrest 15 activists, and said certain “radicals” in the city were blind to the interference of outside forces, in pointed reference to Washington and London.

Hong Kong police arrested 15 activists, including veteran politicians, a publishing tycoon and senior barristers, in raids on Saturday in the biggest crackdown on the city’s pro-democracy movement since the outbreak of mass protests last year, drawing condemnation from the United States and Britain.

They were detained on charges of illegal assembly.

China’s Hong Kong and Macao Affairs Office said the actions of police in the former British colony were made in accordance with evidence police had gathered and were “normal law enforcement measures” to ensure the rule of law and order.

“We resolutely support this,” it said in a statement

U.S. and British criticism failed to take into account the “objective facts” about the illegal protests and violent activities that took place in Hong Kong and are a slander against the police, the office added.

This has “once again exposed the political plot of U.S. and British forces to support and encourage certain anti-China, chaos-in-Hong Kong forces”.

Some opposition and “radical elements” in Hong Kong have vilified the central government at every turn, saying it interferes in the territory’s high degree of autonomy, it said.

“But they ignore the intervention of external forces in the internal affairs of Hong Kong, including the law enforcement of the police and legal authorities and judicial judgements, even seeking foreign countries to sanction Hong Kong,” the office added.

“This is to confuse right from wrong and is double standards. Isn’t this extraordinary!”

China continues to unswervingly support Hong Kong’s police and judicial authorities, and will safeguard national sovereignty and security, as well as Hong Kong’s long-term prosperity and stability, it said.

Hong Kong returned to Beijing’s rule in 1997 under a “one country, two systems” formula that guarantees it broad freedoms not seen in mainland China, and a high degree of autonomy.

But many in Hong Kong fear Beijing is not living up to those promises.

The spike in arrests comes amid deepening fears over Beijing pressure on Hong Kong’s independent judiciary.

In a special report published last week, three of Hong Kong’s top judges told Reuters that the independence of the city’s judicial system is under assault from the Communist Party leadership in Beijing. The judiciary, they said, is in a fight for its survival.

Saturday’s arrests come after several months of relative calm amid a partial coronavirus lockdown but as Chinese and city government officials launch a new push for tougher national security laws for the city.