Six men were rescued from a flooded Chinese coal mine Monday having survived a week underground after at least four of their co-workers were killed, state media said.

Another five workers were still trapped at the colliery at Hegang in the northern province of Heilongjiang.

It flooded on July 20, trapping 15 miners, with investigators blaming the accident on a downpour, the official Xinhua news agency reported.

Xinhua said rescuers started bringing the men out early Monday, and posted images online showing a heavily-wrapped miner being loaded into an ambulance.

"Rescuers are racing to search for the other five workers who have been trapped in the pit for about seven days," Xinhua said.

Xuxiang Colliery -- the scene of the accident -- is privately owned, with an annual output of 150,000 tonnes, it said.

Separately, the news agency said 11 miners who were trapped in a coal mine in the southwestern province of Yunnan since a "cave-in" on Saturday were brought to safety on Monday.

"The trapped miners were brought out on stretchers through a tunnel," Xinhua said, after 1,000 rescuers battled for 40 hours to save the workers.

China -- the world's largest producer of coal -- is grappling to improve standards in the under-regulated sector.

Accidents in Chinese coal mines killed 931 people last year, a top work safety official said in March.

The official number of mining fatalities is declining but some rights groups argue the actual figures are significantly higher due to under-reporting.

Many accidents are caused by corrupt bosses seeking profits over worker safety.