The blaze that tore through a high-rise apartment complex late last month was the world's deadliest residential building blazed since 1980.

Authorities reported a death toll of 159 last week after all affected buildings had been searched.

The toll increased by one on Tuesday after forensic testing revealed that a set of remains already included in the toll turned out to also include a second person, according to police commissioner Joe Chow.

Officers have finished clearing away the fallen scaffolding around the towers and found one piece of "suspected human bone", which is pending tests, Chow added.

The identities of 120 out of the 160 dead have been identified via DNA or fingerprint testing.

Authorities earlier said the blaze at the estate, which was undergoing major renovations, was likely made worse by the use of protective netting on its scaffolding that did not meet fire-resistance standards.

Flames quickly climbed the apartment blocks, which were wrapped with bamboo scaffolding.

The netting, as well as foam boards attached to the windows during the work, contributed to the spread of the fire, authorities said.

Chow said police will begin removing the scaffolding and netting that still cling to the buildings, and will also check for any remaining bodies.

Tsang Shuk-yin, the officer in charge of the police casualty enquiry unit, said six people reported to be missing remain unaccounted for.

Police were relatively sure that three of those people lived at Wang Fuk Court complex, she added.

Hong Kong leader John Lee announced a judge-led "independent committee" last week to investigate the fire.

Police have arrested 15 people from various construction companies for manslaughter, and another six people in connection to fire alarms that failed to sound.