Hong Kong police will deploy more than 6,000 officers on New Year's Eve, local media reported on Tuesday, as protesters plan rallies around the city to urge people not to give up the fight for democracy in 2020.

Protests planned on New Year's Eve include a lunchtime rally in Hong Kong's Central business district with people urged to wear masks and "Don't forget 2019 - Persist in 2020" according to social media posts.

Events dubbed "Suck the Eve" and "Shop With You" are also set for the bar and entertainment district of Lan Kwai Fong in the central business district, as well as promenades near Victoria Harbour, and in major shopping malls.

Police will deploy more than 6,000 officers to deal with potential unrest over the New Year's period, according to the South China Morning Post newspaper, citing unnamed sources.

The police say they have arrested nearly 6,500 people since the protests began escalating in June in what is the worst political crisis faced by the city in decades. The police commissioner, Chris Tang, warned the force would not let up in its arrests to try to restore stability to the city.

On New Year's Day, tens of thousands are expected to join a major pro-democracy march, after it received police approval to proceed, with organisers hoping to sustain the protest movement's momentum into the new year.

The previous such march by organisers, the Civil Human Rights Front, in early December, drew an estimated 800,000 people.

"On New Year's Day, we need to show our solidarity ... to resist the government. We hope Hong Kong people will come onto the streets for Hong Kong's future," said Jimmy Sham, a leader of the group told reporters.

The protests began in June in response to a now-withdrawn bill that would have allowed extraditions to mainland China, where courts are controlled by the Communist Party, and have evolved into a broader pro-democracy movement.

The demonstrations planned for New Year follow a pick up in clashes since Christmas Eve, when riot police fired tear gas at thousands of protesters following scuffles in shopping malls and in a prime tourist district.