KUALA LUMPUR (REUTERS, AFP) - Malaysian Prime Minister Mahathir Mohamad said on Friday (Oct 4) that Hong Kong leader Carrie Lam should resign over the city's increasingly violent pro-democracy protests and warned China would take "harsh action" to end the demonstrations.

He also said the embattled Mrs Lam "is in a dilemma".

"She has to obey the masters, at the same time she has to ask her conscience," he told a press conference.

"Her conscience says that the people of Hong Kong are right in rejecting the (extradition) law. But on the other hand, she knows the consequence of rejecting the law.

"For the administrator (Lam), I think (the) best thing is to resign," Tun Dr Mahathir added.

There has been no let-up in the widespread, sometimes violent, unrest that has beset Hong Kong for nearly four months.

Protesters are angry about what they see as creeping interference by Beijing in their city's affairs despite a promise of autonomy in the "one country, two systems" formula under which Hong Kong returned to China in 1997.

China dismisses accusations that it is meddling and has accused foreign governments, including the United States and Britain, of stirring up anti-China sentiment.

Referring to the bloody 1989 Tiananmen Square crackdown in Beijing, Dr Mahathir on Friday said eventually China sent the military in and "took action, harsh action" to put an end to the demonstration.

"I think in the end, that is what China will do (in Hong Kong).

Dr Mahathir's remarks come ahead of the move by Hong Kong on Friday to ban face masks under a colonial-era emergency law that has not been used in half a century.

It comes shortly after a protester was shot in violent demonstrations that once again shook the city on Tuesday, as Chinese President Xi Jinping celebrated 70 years of Communist Party rule in Beijing.

The 18-year-old protester has been charged with rioting and assaulting a police officer.