Hong Kong lawmakers on Sunday decried the "insane acts" of rioters in Saturday illegal demonstrations across the city, endangering the safety of police officers and innocent bystanders.

As the anti-government protests have entered its 13th week amid ever escalating violence, the 39 legislators from the pro-establishment camp signed a cross-party joint statement calling for united action by the society to deliver the city from chaos by taking a firm stand against violence.

They also implored the police to strictly enforce the laws.

During the Saturday protest, rioters vandalized various public facilities in Admiralty and Wan Chai, set fires on the streets, and threw bricks, corrosives liquids and petrol bombs at police officers, threatening the lives of everyone who happened to be in the vicinity.

Not only have the radicals attached the Central Government Office and the Legislative Council Complex, they have also damaged numerous facilities in several metro stations.

Starry Lee Wai-king, president of the Democratic Alliance for the Betterment and Progress of Hong Kong convened a press conference on Sunday to denounce radical protesters after they vandalized the Legislative Council building for the second time, set bonfires on the streets in different districts, and hurled petrol bombs at police officers.

Saturday's violence has also caused massive damage to the some metro stations, which were still closed on Sunday.

Referring to the clash at Prince Edward station last night, Michael Luk Chung-hung, a member of the Hong Kong Federation of Trade Unions, stressed it was fair and just that the MTR, Hong Kong's rail operator, called for police intervention on security grounds, as the MTR did not have enough staff at the stations to control the crowd.

"Don't turn (train) stations into battlefields…to unleash your rage," Luk urged the protesters.

Meanwhile, in a statement released on Sunday, one of the city's major business groups, Business and Professionals Alliance for Hong Kong, strongly condemned the rioters for escalating violence.

"The rioters have become frenetic and lawless, and we are extremely indignant about and strongly condemn such illegal and violent acts," said the statement.

The violent acts have seriously affected Hong Kong's business development and social stability, the statement said. The BPA voiced its support of the Hong Kong government to introduce effective and concrete measures to stop the violence.

Moreover, the party said it hoped all people in Hong Kong will draw the line in rejecting violence and help Hong Kong to restore social order.