HONG KONG • China warned yesterday that the mass resignations of pro-democracy lawmakers in Hong Kong were a "blatant challenge" to its authority over the city.

Fifteen legislators quit the chamber in protest against the Beijing-sanctioned ouster of four colleagues, leaving the assembly a muted gathering of government loyalists.

"This move makes it clear that dictatorship has descended onto Hong Kong and that the Chinese Communist Party can eradicate all opposing voices in the legislature," said Mr Fernando Cheung, one of the lawmakers. "There's no more separation of powers, no more 'one country, two systems', and therefore no more Hong Kong as we know it."

The resignations sparked a furious response from Beijing's Hong Kong and Macau Affairs Office.

"It once again showed their stubborn confrontation against the central government and a blatant challenge to the power of the central government. We severely condemn this," a statement said. "We have to tell these opposition lawmakers, that if they want to use this to advocate a radical fight, and beg for foreign forces to interfere, and once again drag Hong Kong into chaos, that's a wrong calculation."

Inside the chamber, government loyalists discussed a transport Bill, but without any of the rambunctious debate that has been the mark of Hong Kong's semi-democracy in recent years.

Hong Kong Chief Executive Carrie Lam, a Beijing appointee, on Wednesday was granted the power to turf out any legislator whom she deems insufficiently patriotic, without recourse to the city's courts.

She immediately made use of those powers, kicking out four lawmakers she said were a threat to national security, and sparking criticism both at home and abroad, with the United States threatening further sanctions on regime figures.

US national security adviser Robert O'Brien said China's latest clampdown in Hong Kong shows that the "one country, two systems" arrangement for the territory amounts to a "fig leaf" for dictatorship.

Britain yesterday said China had broken its main bilateral treaty on Hong Kong, cautioning that it would consider also sanctions as part of its response.

"Beijing's imposition of new rules to disqualify elected legislators in Hong Kong constitutes a clear breach of the legally binding Sino-British Joint Declaration," Foreign Secretary Dominic Raab said.

The city's last colonial governor Chris Patten said the move demonstrated Beijing's "total hostility to democratic accountability, and those who wish to stand up for it".

The European Union called on China to "immediately reverse" the rules placed on Hong Kong's legislature and urged the legislators' "immediate reinstatement".

Any sanctions would infuriate Beijing and accelerate a deterioration in relations between the nations on a variety of issues.

China's Foreign Ministry spokesman Wang Wenbin rejected the international criticism. "We urge the relevant people to strictly abide by the basic norms of international law and international relations, stop any form of interference into China's internal affairs, of which Hong Kong affairs are a part," he said.

The exodus of opposition lawmakers neuters one of the last forums for dissent in Hong Kong, as its media reels under a crackdown unleashed by the national security law and Beijing loyalists target the legal system that has underpinned the city's success as a finance hub.

REUTERS, BLOOMBERG, AGENCE FRANCE-PRESSE