Policemen close-off a road to prevent protesters from continuing to march in Sha Tin District in Hong Kong, on Sunday.

Police and protesters clashed again in Hong Kong Sunday as unrest caused by a widely-loathed plan to allow extraditions to mainland China showed no sign of abating.

Police used pepper spray and batons against small groups of protesters who took over a road on the sidelines of another huge rally in Sha Tin, a district that lies between the main urban sprawl around the harbour and the Chinese border.

Masked protesters responded by building barricades from metal fencing and a stand-off with riot police ensued.

A protester holds a placard as she takes part in a march with thousands of others in Sha Tin District in Hong Kong, on Sunday.

Hong Kong has been rocked by more than a month of huge largely peaceful protests — as well as a series of separate violent confrontations with police — sparked by a law that would have allowed extraditions to mainland China and other countries.

Last month, parliament was trashed by hundreds of masked, youth-led protesters in unprecedented scenes.

The bill has since been postponed, but that has done little to quell public anger which has evolved into a wider movement calling for democratic reforms, universal suffrage and a halt to sliding freedoms in the semi-autonomous hub.

Protesters are also demanding the bill be scrapped entirely, an independent inquiry into police use of tear gas and rubber bullets, an amnesty for those arrested, and for the city's unelected leader Carrie Lam to step down.

Tens of thousands marched through Sha Tin on Sunday, the fifth week in a row that Hong Kong has seen such huge rallies.

Almost all have ended with violence between police and a minority of hardcore protesters.

"We have marched so many times but the government still didn't listen, forcing everyone to take to the street," Tony Wong, a 24-year-old protester on the Sha Tin march, told the media.

Many protesters see the rallies as part of an existential fight against an increasingly assertive Beijing.

Agence France-Presse