Sixteen district councillors face disqualification after the government raised doubts about the oaths they took on Monday.
They were among 50 councillors from Tai Po, Sai Kung, Sha Tin and North District who pledged their allegiance before the oath administrator, Home Affairs Secretary Caspar Tsui, in the third oath-taking ceremony held by the government.
Among the 16 whose oaths were questioned and have been asked to submit additional information to Tsui is Ricky Or from Sai Kung, who's been charged with violating the national security law over the Legislative Council primaries case.
He said after the ceremony on Monday that it's his duty to take the oath.
The oath of the chairman of the Sha Tin District Council, Raymond Li, was also called into question.
He said after the ceremony that he believed he'll be disqualified, but took the oath anyway, saying it's his election pledge to serve his full four-year term.
"We take the oath to do all we can to serve the public, until the very last moment," he said.
Three councillors – Chan Nok-hang and Chan Pui-ming from Sha Tin, as well as Yu Tsun-ning from Sai Kung – announced their resignations ahead of Monday's ceremony.
Of the 79 councillors from Hong Kong Island and Kowloon who took their oaths last month, 17 were disqualified after Tsui raised questions about the oaths which were subsequently ruled invalid.
The fourth and final batch of councillors – from Yuen Long, Tuen Mun, Tsuen Wan, Kwai Tsing and the Islands District – will take the oath on Friday to uphold the Basic Law and bear allegiance to the SAR.