The Central Government suffers an annual loss of Rs 1,800 crore on account of thousands of coal mafia,which involve themselves in illegal mining across different states,a senior official said. "Thousands of coal mafia (gangs) active in coal-producing belts,including that of Coal India Ltd (CIL),plunder about six million tonnes of coal annually. Going by current prices in the domestic market,this amounts to Rs 1,800 crore a year," the official said. On an average,coal sells for nearly Rs 1,000 per tonne in the domestic market. He said that the mafia is primarily active in the main coal-producing states of Jharkhand,Orissa and Chhattisgarh - which are also affected by Maoist violence. Meanwhile,the Centre has asked states to form high-level committees to curb illegal mining.