The Hong Kong government said on Friday that it had tested more than 20 samples of the protective mesh of the insulation of the apartment complex, where a fire broke out that killed 151 people, Reuters reported, BTA reported.
Seven of the samples taken from four blocks of the complex did not meet fire safety standards, the authorities said.
The fire broke out on Wednesday afternoon in eight 31-story buildings and continued to burn until Friday morning, when it was completely extinguished. The death toll has now risen to 151, and authorities believe they may find more bodies.
The scale of the tragedy has shocked the entire territory and prompted calls for those responsible to be held accountable.
Hong Kong's Director of Criminal and Security Police Chan Tung said that an investigation into manslaughter was launched immediately after the tragedy, which "has led to the arrest of 13 people - 12 men and one woman". The complex, which has around 2,000 apartments, is being renovated, but residents are still not allowed to return to their homes.