A government-led investigation into the fire at Hong Kong's Wang Fuk Court has found that some mesh netting used to wrap the buildings — to protect against falling debris during renovation work — failed to meet fire retardant requirements, as the tragedy's death toll climbed to 151.

One of the city's deadliest blazes in decades, the tragedy pulled at the heartstrings of people across the country.

Xia Baolong, director of the Hong Kong and Macao Work Office of the Communist Party of China Central Committee and the Hong Kong and Macao Affairs Office of the State Council, received a detailed report on the relevant situation in Shenzhen, the Guangdong city neighboring Hong Kong, on Monday, according to a statement from the office.

The authorities said on Monday that seven out of the 20 mesh samples collected from the buildings did not meet flame retardant standards.

All eight buildings in the housing estate, completed in 1983, had been covered in bamboo scaffolding and green mesh netting since last year while the buildings underwent major maintenance work.

At a news conference on Monday, Danny Woo Ying-ming, commissioner of the Independent Commission Against Corruption, said investigations had found that some of the original netting had been replaced by cheaper substandard material after it was damaged by super typhoon Ragasa in September.

To deceive inspectors, some of those suspected of using the substandard netting procured a small amount of good quality netting for use on lower parts of the buildings where it was more accessible.

The inferior netting was used in areas that were harder for inspectors to reach, said Eric Chan Kwok-ki, chief secretary for the administration.

Chan criticized those suspected of using the low quality netting for "sacrificing many lives for petty gains" as the price difference between compliant and noncompliant materials is just a few dozen Hong Kong dollars per roll.

He pledged that the authorities would pursue the investigation to the end.

If other buildings are found to be also using substandard netting, the government will carry out thorough investigations, Chan added.

The discovery of inferior mesh netting contradicts a previous statement made by Secretary for Security Chris Tang Ping-keung, in which he said the mesh materials used in the housing estate's renovation work did meet building standards according to preliminary tests.

He explained at Monday's media conference that his error was because conditions at the time had made it impossible to collect a large number of netting samples.

Police said 13 people have been arrested — 12 men and one woman, including engineering consultants, contractors and scaffolding work supervisors — on suspicion of manslaughter. There may be further arrests as the investigation is ongoing, the police said.

The police found five more bodies on Monday in their search, bringing the death toll from the fire to 151, including eight domestic workers — seven from Indonesia and one from the Philippines.

Among the recovered bodies, over 30 are yet to be identified. Some of the newly discovered remains had almost been reduced to ashes.

Police expect to complete the search and evidence collection work within three weeks at its current speed.

Police said they will do their utmost to recover bodies and any identifiable items from the site so that families can bid their final goodbyes.

People from across Hong Kong society have continued to help survivors of the fire with resources, mental support and technology.

An online platform codeveloped by the government and the IT sector to facilitate material donations began operating on Monday, enabling the authorities to better deal with information and distribute supplies to those in need.

On the home page of the website, there are three buttons, including one linked to a donation registration form, one that calls an artificial intelligence assistant to deal with enquiries, and one that navigates to the latest information.