China should continue to import coal in "appropriate" volumes, and domestic coal companies are encouraged to invest in overseas coal mines, the head of National Energy Administration's coal department said in an article published in state-controlled People's Daily Friday.

Coal imports can help China offset its trade imbalance, while investment in overseas coal mines can improve local coal firms' management skills and ensure national energy security, Fang Junshi said in the report.

China should also limit the pace of its coal output growth, Fang said. He didn't indicate an acceptable pace or appropriate import volume level.

The world's largest coal producer has stepped up coal imports since last year to fuel its rapidly-expanding economy, shipping in 125.8 million metric tons last year, more than triple 2008's level.

Coal shipments from overseas totaled 133.93 million tons from January-October this year, up 38% from the same period last year.

NEA Director Zhang Guobao said in a speech Oct. 27 that he doesn't favor the country's coal output expanding above 4 billion tons a year.

Policymakers are mulling an annual cap of between 3.6 billion tons and 3.8 billion tons in the next five-year plan, running from 2011 to 2015, to prevent oversupply and curb consumption of the polluting fuel, the official Xinhua News Agency reported previously.

The nation has pledged to cut carbon emissions per unit of gross domestic product by 40%-45% by 2020 from 2005 levels.

China's trade surplus grew to $27.15 billion in October from $16.9 billion in September, which added to the already high pressure from the U.S. and other countries seeking a stronger Chinese currency to narrow their trade gaps with China.