Pro-democracy groups have retained their one-third veto bloc in Hong Kong's 70-seat Legislative Council (Legco) following an election marked by a record voter turnout and the emergence of candidates calling for independence from China.

Official results show that pro-democracy candidates won 30 of the 70 seats, more than is required for the opposition to have veto power to block attempts by Hong Kong's government to enact unpopular or controversial legislation, according to AFP news agency.

Several pro-independence candidates emerged victorious in Sunday's election - the first since the so-called Umbrella Revolution of 2014.

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Nathan Law Kwun-chung, the former student leader of the Umbrella Revolution and key figure in the 2014 pro-democracy movement, which saw parts of downtown Hong Kong occupied for 79 days in protest against a controversial electoral reform bill, was declared a winner on Monday.

Law, 23, contested as a candidate of the Demosisto party, which wants a referendum for Hong Kong residents on whether they should stay part of China.

"I think Hong Kongers really wanted change," he said, celebrating his win.

"Young people have a sense of urgency when it comes to the future," he added.

In a brief statement carried by China's official Xinhua news agency on Monday, China's Hong Kong and Macao Affairs Office said it was "resolutely opposed" to any kind of Hong Kong independence activities in the territory's legislature, Reuters news agency reported.

Hong Kong independence is contrary to China's constitution, harms national sovereignty and security, and will harm Hong Kong's prosperity and stability, it added.

At some polling stations there were long queues until until 2:30am local time on Monday morning - four hours later than the scheduled cut-off time for voting - in an election which saw a turnout of 58 percent of the city's 3.8 million eligible voters.

Pro-democracy rallies

The city-wide vote was the biggest since mass pro-democracy protests in 2014 and saw candidates fighting for seats in the Legco as concerns grew that China is tightening its grip on the semi-autonomous city.

"There have been some emotional scenes here at the election centre as the results came in, bearing out the expected trend that has been predicting the rise of the so-called localist movement," Al Jazeera's Rob McBride, reporting from Hong Kong, said.

"These new parties and groupings have grown largely out of the Occupy movement two years ago, groups with a very different agenda from the mainstream pro-democracy groups.

"Some key leaders of the pro-democracy parties have lost their seats."

Only 40 out of 70 total seats are directly elected by the public, while special-interest groups representing a range of mostly pro-China businesses and social sectors select the other 30 legislators.

The pro-China contingent will continue to dominate the legislature, as they hold on to their seats in the functional constituency.

"The way the Legislative Council is structured, it still remains effectively a pro-establishment body. But even so, Beijing and Hong Kong will be worried about the results that show how polarised Hong Kong society has become," the Al Jazeera correspondent said.

Sunday's election was marred by accusations of fraud, an uncommon occurrence in the city that was transferred to Chinese control from Britain in 1997 under a "one country, two systems" agreement.

Leung Chun-ying, the city's chief executive, in a statement on Sunday night praised the conduct of the commission in ensuring fair elections.