Protesters cover their faces to conceal their identity as they retreat away from riot police during the demonstration.

China's top legislature said Hong Kong courts have no power to rule on the constitutionality of legislation under the city's Basic Law, which includes a proposed ban on face masks, state news agency Xinhua reported on Tuesday.

The statement came a day after Hong Kong's High Court ruled that a ban on wearing face masks during public demonstrations that have rocked the financial hub for more than five months was unconstitutional.

"Whether the laws of the Hong Kong Special Administrative Region comply with the Basic Law of Hong Kong can only be judged and decided by the Standing Committee of the National People's Congress," Yan Tanwei, a spokesman for the Legislative Affairs Commission of the Standing Committee of the National People's Congress, said in a statement.

"No other authority has the right to make judgments and decisions," the statement said.

Embattled Hong Kong Chief Executive Carrie Lam proposed enacting a ban on wearing face masks as the pro-democracy demonstrations escalated.

Protesters had been using masks to hide their identities in public. The proposal was widely criticized by supporters of the anti-government movement, who saw it as posing a risk to demonstrators.

Hong Kong's High Court ruled on Monday that colonial-era emergency laws, which were revived to justify the mask ban, were "incompatible with the Basic law", the mini-constitution under which Hong Kong was returned to China in 1997.