Beijing - The death toll rose to 56 in a mudslide that buried a market and other buildings in northern China's Shanxi province, state media said Wednesday.

More than 30 mechanical diggers were aiding several hundred rescue workers who had already searched about 70 per cent of the debris left by Monday's mudslide, the semi-official China News Service said.

The agency said the number of people missing was still under investigation, but one earlier state media report said several hundred people could have been trapped.

The State Administration of Work Safety said heavy rain in recent days caused a dam to burst and flood a waste reservoir downstream at an iron mine in a valley near Shanxi's Linfen city.

The dam at the reservoir also burst, leaving at least 56 dead and 35 injured, five of them seriously, by Tuesday evening, the agency said.

Earlier reports said police detained the owner and eight others involved in running the Tashan mine, part of which was said to be operating illegally.

"The owner of the mine conducted illegal production, which led to the bursting of the dam," state broadcaster China Central Television said.

The area around Tashan has several iron ore mines that employ many migrant workers from Shanxi and other provinces, making it difficult for local officials to identify the victims of the mudslide, reports said. (dpa)