Pro-democracy candidates won nearly half of the seats in Hong Kong's local elections, according to partial returns on Monday, as voters sent a clear signal of support for the anti-government protests that has rocked the Chinese territory for more than five months.

A record 71 per cent of the city's 4.1 million registered voters cast ballots on Sunday, well exceeding the 47 per cent turnout in the same election four years ago, election officials said.

So far, pro-democracy candidates have won 201 out of 452 seats in 18 district councils. Previously, the bloc had fewer than a third of the seats.

Among the winners were former student leaders and a candidate who replaced prominent activist Joshua Wong, the only person barred from running in the election. Rally organiser Jimmy Sham, who was beaten by hammer-wielding assailants last month, also triumphed, as did a pro-democracy lawmaker who had part of his ear bitten off by an assailant.

Hong Kong's largest pro-Beijing political party suffered the biggest setback, with at least 155 of its 182 candidates defeated. Among the losing incumbents was controversial lawmaker Junius Ho, who was stabbed with a knife while campaigning this month.

The pro-democracy camp hailed its strong gains in the normally low-key race as a 'victory' for the Hong Kong people. Candidates said the city's embattled Chief Executive Carrie Lam must heed protesters' demands, including free elections for the city's leader and legislature, and an independent probe into alleged police brutality.

'We won a small battle today but it shows that Hong Kong people have a chance to win the war. We will fight on,' said Henry Sin Ho-fai, a pro-democracy candidate who won.

The record turnout showed 'a great groundswell in Hong Kong who believes in democracy,' said David Alton, a member of the British House of Lords who is among the international election observers invited by Hong Kong's civil society groups.

During the months of demonstrations, protesters have smashed storefronts of businesses seen as sympathetic to China, torched toll booths, shut down a major tunnel and engaged in pitched battles with police, countering tear gas volleys and water cannons with torrents of gasoline bombs. More than 5,000 people have been arrested in the unrest that contributed to Hong Kong's first recession in a decade.

Voter Christina Li said it was important for older people like herself to support the youth at the forefront of the protests.

'Younger generations might not be able to enjoy the rights that we are enjoying now,' she said as she waited in line outside a polling station. 'We cannot take it for granted.'

Many people in Hong Kong share the concern of protesters about growing Chinese influence over the former British colony, which was returned to China in 1997. The protests started in June over a now-abandoned extradition bill that would send criminal suspects for trials in mainland China. But the movement has since swelled into an anti-China campaign.

Voting was peaceful amid tight security, with hardly anyone seen wearing protesters' trademark black clothing or face masks. Many voters turned up early to cast their ballots, leading to long lines that extended for blocks.

The vote is the only fully democratic one in Hong Kong. Members of the legislature are chosen partly by popular vote and partly by interest groups representing different sectors of society, and the city's leader is picked by a 1,200-member body that is dominated by supporters of the central government in Beijing.

Dixon Sing, a political science lecturer with the Hong Kong University of Science and Technology, said the democrats' victory was 'tantamount to a rejection of the hard-line policy of Beijing and the Hong Kong government.'

A win would bolster the democrats' influence and give them 117 seats in the panel that elects the city's leader, but Beijing isn't likely to soften its stance or make any concessions to the protesters, he said.

There has been a rare break in the violence in recent days as protesters, eager to validate their cause at the ballot box, hit the pause button to ensure the polls wouldn't be postponed.

Hong Kong leader Carrie Lam, who is reviled by the protesters, said after voting on Sunday morning that she hoped the calm will last.

'I hope that ... the election will show that everyone doesn't want Hong Kong to return to chaos again, that we want a way out of this crisis so that we can have a fresh start,' Lam said.