North China's Inner Mongolia Autonomous Region has replaced neighboring Shanxi Province as the country's largest producer of coal, local authorities said Friday.

In 2009, Inner Mongolia reported coal output of 637 million tonnes, 22 million tonnes more than Shanxi, China's top coal producing region for 30 years, said a statement from the regional administration of coal mine safety.

Last year, Inner Mongolia's coal production increased 37 percent year on year, and it was expected to hit 730 million tonnes in 2010, the statement said.

Shanxi saw a decline of 4.7 percent of its coal output year on year in 2009, it said.

Since 2004, Inner Mongolia had cut the number of its collieries from 2009 to 501, while expanding their annual capacity from 140,000 tonnes to 1 million tonnes, it said.

It also contained the country's largest verified coal reserves of 700 billion tonnes, which more than doubled the number of Shanxi, said a spokesman with the regional department of Land and Resources.

In 2009, Shanxi launched a major coal industry consolidation to optimize operations, which led to closure of collieries with an annual capacity lower than 300,000 tonnes, Chen Chuanping, vice governor of Shanxi, told a news briefing early this month.