Former democracy lawmaker Au Nok-hin helped organise the weekend poll that saw more than 610,000 people vote in what was widely seen as a symbolic protest against the sweeping legislation imposed on the city by Beijing.

"Withdrawal is the only choice (I have, to) ... protect myself and others," Au said in a Facebook post.

The primary polls were aimed at selecting democracy candidates to stand in September elections for the Legislative Council, Hong Kong's governing body.

Results from the primaries so far show 16 candidates from the "resistance" or "localist" camps were elected, outshining the traditional democrats who secured 12 votes.

The strong performance of the younger generation reflects a potential change of guard to a more radical grouping likely to rile authorities in Beijing.

The remaining results are expected later on Wednesday.

Some voters are frustrated with Hong Kong's more moderate traditional democracy groups at a time when Beijing is tightening its grip on the city with a new security legislation seen by many as the latest attempt to crush freedoms.

The democrats are gearing up for elections on September 6, when they hope to secure a majority in the 70-seat legislature for the first time.

In comments that critics said were aimed at instilling fear in the community, Beijing's top office in the city, the Hong Kong Liaison Office, the Chinese government agency Hong Kong and Macau Affairs Office, and the city's leader Carrie Lam have all said the primaries could violate the new national security law.

A spokesman for the Liaison Office said the pro-democracy camp's bid for a legislative majority was an attempt to carry out a 'colour revolution' in Hong Kong, referring to populist uprising in other parts of the world.

The new security law punishes what Beijing broadly defines as secession, subversion, terrorism and collusion with foreign forces with up to life in prison and sees Chinese intelligence agents operating officially in the city for the first time.

Australian Associated Press