The flooding was reported at 8:44pm in a pit of the Fushun Mining Group, a state-owned company in Fushun, a major industrial city east of the provincial capital Shenyang, said a source with the provincial safety watchdog.

He said 29 miners were working on platform No. 73003 of the Laohutai Mine when it was drowned.

Search and rescue work started shortly after the flooding.

The pit has been closed for a safety overhaul.

Laohutai, which translates into "tiger's platform", is a 100-year-old mine still with 160 million tons of proven coal reserves. It employs 7,200 people and produces 3.35 million tons a year.

It is also one of the country's 45 most dangerous coal mines for its high risk of flooding, fire and gas leak.