Photo taken on Dec. 21, 2015 shows the landslide site of an industrial park in Shenzhen, south China's Guangdong Province. A total of 91 people remain missing as of early Monday morning, after a landslide buried or damaged 33 buildings in the industrial park in Shenzhen City on Sunday, according to local authorities. [Photo: Xinhua]

Three more suspects implicated in the deadly landslide in Shenzhen last month were arrested on Monday.

The suspects, who were not identified, are accused of failing to ensure safety management, which eventually led to the major accident.

So far 20 people have been arrested over the accident on Dec. 20.

In the meantime, authorities say they are also investigating 12 others for abuse of power and dereliction of duty.

Among them are the head of a local urban management bureau and a deputy head of the municipal service center.

The landslide occurred after a huge waste pile collapsed and left 69 people dead and eight people missing in the southern Chinese city.

Authorities have determined it was not a natural disaster.