The output of China's energy-guzzling coke industry rose 21 percent on last year to 156.8 million tons in the first half, according to the latest figures from the China Coking Industry Association (CCIA).

The figures came despite the warning from Huang Jingan, CCIA president,in March that China, the world's largest coke exporter, should reduce production to cut power consumption and pollution as well as the soaring trade surplus.

The rise in coke output was propped up by the rapid growth in the steel, chemical engineering, nonferrous metal and mechanical industries, with the iron and steel industry consuming 80 percent of the coke.

Coke is in short supply globally and it is estimated that China's coke resources will be depleted in 40 years.

The central government is considering levying an extra tax on coke exports, which account for half of the world's annual coke consumption. China has been exporting about 15 million tons of coke annually in recent years.

The government levied a five-percent tax on coke exports from Nov. 1, last year, but it proved ineffective in suppressing rising exports, which rose by 38 percent in January.

Insiders estimate coke exports this year could be reduced to around 10 million tons with the introduction of a 20-percent tax and seven million tons with a fifty-percent tax.

Xu Guangcheng, former president of CCIA, said that coke exports should be kept between five to six million tons.