SHENZHEN (REUTERS) - Rescuers pulled one body from a mountain of rubble on Tuesday (Dec 22) after working through the night with drones and heavy machinery in search of more than 80 people missing since a giant flow of mud and construction waste engulfed buildings in southern China.

The body recovered from the sea of mud and debris was the first confirmed casualty since the landslide swallowed 33 buildings in the Hengtaiyu industrial park in the southern boom town of Shenzhen on Sunday, the official Xinhua news agency reported.

Thousands of rescue workers scoured through the 380,000 sq m site lit up with floodlights, photos on social media showed, using heavy diggers to reach possible survivors trapped under mud up to 10 m deep.

The People's Daily newspaper said in its microblog post that 81 people were still missing.

A report carried on the China defence ministry's website said police and military forces were in a "race against time"and were using drones to map out the scene and life-detecting probes to find possible signs of survivors.

It said rescuers had freed some people trapped in damaged buildings. The number of missing had been listed as 85 late on Monday.

The multi-storey buildings toppled within seconds after the mudslide smashed into them in Shenzhen's Guangming New District.

The mud had come from an overfull waste dump nearby, which official reports said should have been closed in February.

The frequency of industrial accidents has raised questions about safety standards in China after three decades of breakneck growth in the world's second-largest economy.

Just four months ago, more than 160 people were killed in big chemical blasts in the northern port city of Tianjin.

Chinese Premier Li Keqiang has ordered a probe into the landslide in Shenzhen, a developed metropolis and business hub just across the border from Hong Kong.