HARBIN - Twenty-six miners were trapped underground when an illegal coal mine in northeast China's Heilongjiang Province flooded Tuesday, the local government said.

The flooding happened mid-day, when 45 miners were working in a pit of the Hengtai Coal Mining Co. Ltd. in Boli County in the coal-rich city of Qitaihe, a spokesman with the provincial work safety administration said.

He said 19 miners escaped and 26 others were stranded in the pit.

Rescue efforts are underway, he said.

The flooded pit, with an annual output of 30,000 tonnes, was one of the small mines that should have stopped production and been integrated into larger mines, the spokesman said.

He said the mine was operating illegally when the accident happened.

China in recent years has moved to close down small collieries to improve safety and efficiency in the mining industry.