The death toll in Hong Kong's most devastating fire in decades reached 159 on Wednesday as police completed their search of the interiors of all seven residential blocks of Wang Fuk Court that erupted in flames a week earlier.

Another three bodies were found on the final day of the searches of the units.

Police Commissioner Joe Chow said 140 of the bodies have been identified, involving 49 males and 91 females aged between one and 97.

But another 31 people remain unaccounted for and suspected human remains have been found in the flats.

"We have found suspected human bones inside different flats, we have to conduct more tests. Of course, for people who have reported missing family members, we hope they can assist with DNA comparisons," Chow said at a media briefing near the scene in Tai Po.

"We could use other forensic methods such as comparing teeth to identify the missing. It's our responsibility to ensure that they can have a final reunion with their families."

Chow said 152 bodes were found in Wang Cheong House and Wang Tai House, the first and second blocks to catch fire.

He said officers had revisited the flats of people reported missing, even using their bare hands to search through the rubble.

He said the search for bodies will now move to other parts of the buildings, such as the remnants of the bamboo scaffolding covering the blocks.

"We have not finished our work. As you can see the scaffolding, a lot of bamboo has fallen down. We still need to do some work... to see if any bodies were covered by the bamboo," Chow said.

He also added that the force has arrested six men connected to a fire safety device contractor on suspicion of making false declarations regarding the fire alarms in the buildings that failed to go off during the blaze.