The death toll from last month's apartment complex blaze rose to 160 after an additional body was identified, police said on Tuesday, adding that six people were still listed as missing.

"The public's solidarity with the victims of the fire has shown the depth and resilience of the civic spirit in Hong Kong," UN human rights chief Volker Turk said in a statement.

"The people of Hong Kong understandably want answers and accountability, so that the hundreds of victims are properly compensated, and to avoid such a tragedy occurring again."

Hong Kong was once home to spirited political activism but that has faded since Beijing imposed a strict national security law in 2020 following huge pro-democracy protests in the Chinese finance hub.

Authorities have warned against crimes that "exploit the tragedy" and arrested a 71-year-old man for sedition, following earlier reports of three fire-related sedition arrests.

"I am deeply concerned by reports that the territory's draconian security laws are being applied against individuals who have called publicly for a transparent and independent inquiry, a review of construction oversight, government accountability, and support for affected residents," Turk said.

"I urge the authorities to drop these cases against those seeking accountability."

Turk said several provisions under the national security law did not comply with international human rights law.

"The cumulative impacts of these laws reflect a systemic erosion in enjoyment of human rights, including the fundamental freedoms of expression, peaceful assembly and association in what was once a vibrant hub for civil society, vigorous debate on public policy, and independent media in the region," said Turk.

Hong Kong on Sunday held its second "patriots only" legislative elections under rules that Beijing imposed in 2021, which slashed directly-elected seats and tightened political vetting for candidates.

"The compelled dissolution of major political parties has effectively eliminated organised political opposition," said Turk.

He said political pluralism provided essential checks and balances needed for the democratic accountability of public authorities.

"There is an opportunity to restore meaningful civic space in Hong Kong, by rolling back these measures that restrict political participation and suppress dissent," he said.