Authorities in Hong Kong have ordered the removal of scaffolding mesh from buildings undergoing renovations by Saturday, as investigations continue into the Chinese territory's deadliest blaze in decades.

It is now known that 159 people died as a result of the fire last Wednesday at the Wang Fuk Court housing complex - with 31 still missing.

Investigators have found that a protective netting used around the complex, which had been undergoing extensive renovations, failed to meet flame retardant standards.

Secretary for Development Bernadette Linn Hon-ho said new guidelines for testing materials used in scaffolding would be issued next week.

Around 200 private residential and 10 public buildings are currently undergoing renovations in Hong Kong.

The South China Morning Post, which is based in the territory, says about 300 buildings will be affected by the removal order.

"I assure the public that we will chase to the end the accountability of any contractors using substandard scaffolding mesh," Linn was quoted as saying.

Samples had already been taken from mesh for testing, she added.

At Wang Fuk Court, flames spread quickly across the separate tower blocks on protective mesh netting and other flammable materials on the outside of the buildings, officials said.

Police have made at least 15 arrests for manslaughter as the investigation into the cause of the fire proceeds.

On Wednesday, they said they had completed their searches of the interiors of all seven of the complex's towers and would now look for bodies in other parts of the buildings such as the remnants of the bamboo scaffolding.

"We have not finished our work," Police Commissioner Joe Chow said.

"As you can see... a lot of bamboo has fallen down. We still need to do some work... to see if any bodies were covered by the bamboo."

He added that 140 of the 159 bodies found to date had been identified and were those of 49 males and 91 females, aged between one and 97, Radio Television Hong Kong reports.

A married couple in their 70s, who lost their home in the blaze, returned to the charred site with their daughter on Wednesday, Reuters news agency reports.

"It all happened within just an hour or two," said the mother, whose name was given only as Leung.

She continued: "I stood there watching as one block after another went up in flames, my legs felt so weak I could hardly stand. When I saw it, I felt completely helpless. I still don't understand how the fire could spread so fiercely, devouring one building after another. It was terrifying.

"The bamboo scaffolding cracked and there was banging that sounded like exploding windows, the flames were completely out of control."

Her daughter, Bonnie, added: "We also hope the truth will come out - whether there were hidden hands behind this, corruption or any improper dealings."