The General Statistics Office said coal output in January-June rose 8 percent from a year ago to 22.42 million tonnes.

Vietnam, struggling to meet soaring energy demand at home, plans to slash coal exports this year by more than 32 percent to about 22 million tonnes to save more for new power plants, officials from the Industry and Trade Ministry have said.

Vinacomin, the country's top coal producer, has forecast coal output this year could rise to 43 million tonnes, beating previous industry projections of 40 million tonnes.

Last year, its coal production rose 11.5 percent to 41.2 million tonnes.

As part of the move to save coal, the government in April launched a crackdown on coal smuggling to China, which was estimated to be as high as 10 million tonnes last year, with police intercepting more than a hundred ships carrying illegal coal cargoes near the Chinese sea border.

Vinacomin said it had stop the cross-border sales of coal via Van Gia port in the northern province of Quang Ninh from June 1 and only allowes its subsidiary Coalimex-TKV to export coal to China.

Power demand in Vietnam is expected to grow between 18 percent and 20 percent annually, prompting the government to seek ways to diversify energy sources including coal, water, natural gas, wind power and nuclear.

Vietnam is forecast to start importing coal from 2012 with the purchases rising to 34 million tonnes in 2015 and 114 million tonnes by 2020, the Industry and Trade Ministry said in a report to the government in March.

Vietnam has raised export tariffs on minerals, including crude oil and coal, to 20 percent from June 16 in a bid to limit coal exports. Crude oil sales were subject to a previous 8 percent duty while that on coal had been 15 percent.