Protesters have used face masks to avoid identification along with yellow helmets, goggles (AFP Photo)

Hong Kong will soon ban the wearing of face masks at public protests, local media reported Thursday, in a clampdown on pro-democracy rallies that have rocked the strife-torn city.

Seething public anger against Chinese rule of the semi-autonomous city has underscored increasingly violent confrontations between police officers and demonstrators, with no sign of an end to nearly four months of unrest.

Protesters have used face masks to avoid identification -- along with yellow helmets, goggles and respirators to protect themselves from tear gas and police projectiles.

Officials plan to deter future gatherings by introducing the ban under a colonial-era emergency law that bypasses the city's legislature, according to the South China Morning Post.

City leader Carrie Lam is expected to announce the measure on Friday, the Post reported.

Pro-Beijing lawmakers in the financial hub have renewed their calls for Lam to introduce the emergency ordinance since Tuesday, when protests in Hong Kong overshadowed 70th anniversary celebrations for the founding of the People's Republic of China.

In the worst day of violence since the protests movement began, police shot and wounded a teenager who attacked officers with a stick, and fired a record 1,400 rounds of tear gas to disperse crowds across the city.

"If we had the law... then this would have a deterrent effect on some people," lawmaker Elizabeth Quat told reporters on Thursday.

"We are not talking about peaceful protesters. We are talking about people who use illegal violence," she added.

But pro-democracy lawmaker Dennis Kwok said the emergency law would signal "the beginning of a slip towards an authoritarian state".

"The authorities by now should have listened to the Hong Kong people. Their yearning for freedom, liberty and democracy, is not going to go away," he said.

Reports of the face mask ban lifted the Hong Kong stock market, which ended the day 0.3 percent higher.

"The anti-mask law at least gives investors some hope that it could be a way to cool down the protests," said Steven Leung, at UOB Kay Hian (Hong Kong).

"Some protesters might think twice if they can be identified during protests."

Hong Kong's protests were ignited by a now-scrapped plan to allow extraditions to the mainland.

But after Beijing and local leaders took a hardline they snowballed into a wider movement calling for democratic freedoms and police accountability.

With Hong Kong leader Carrie Lam seemingly unwilling or unable to find a political solution, police have been left to battle increasingly radicalised protesters.