Hong Kong government efforts and last-ditch campaigning by candidates were struggling on Sunday to boost turnout in an overhauled “patriots”-only legislative election, the first under a sweeping new security law.

After eight hours of voting, turnout was more than 10 percentage points below the previous Legislative Council election five years ago.

The election — in which only candidates screened by the government as “patriots” can run — has been criticised by some activists, foreign governments and rights groups while mainstream pro-democracy parties are not taking part.

Turnout is a central issue, as observers consider it a barometer of legitimacy in an election where pro-democracy candidates are largely absent, more than a third of the seats will be selected by a committee stacked with Beijing loyalists and a crackdown under a China-imposed national security law has jailed scores of democrats. Civil society groups have disbanded.

“Clearly, the government’s objective is to secure a high turnout. Otherwise it may delegitimise this election,” said Jean-Pierre Cabestan, a professor of political science at Hong Kong’s Baptist University.

The government on Saturday sent blanket text messages to Hong Kong residents urging people to vote, and some critics calling on people to stay away as a protest.

After eight hours of voting, official figures showed 21.02 per cent of the electorate had voted, down from 31.16 per cent at the same point in 2016.

Polls close at 10.30pm, with results expected on Monday.

Chief secretary John Lee, a former security chief, urged people to turn out, saying those excluded were “traitors” who wanted the vote to fail.

“The situation is critical,” Starry Lee, the head of the largest pro-Beijing party DAB said in a recorded loop played on a loudspeaker in the working class Wong Tai Sin district. “I urge everyone to vote.”

Lee’s appeal did not convince local fruit seller Jack Ng, who said he would not join an election that was neither fair nor democratic. “I don’t understand why she is campaigning. She will win for sure, it is absurd,” said Ng.

Others who said they would not vote expressed anger at the changes that some said had turned the poll into a “selection” and the legislature into a “puppet”.

Hong Kong leader Carrie Lam, among the first to vote, told reporters that the government “had not set any target” on the turnout rate.