Thermal coal prices at Australia's Newcastle port, a benchmark for Asia, fell for a second week, declining 3.6 percent.

The weekly index for power-station coal prices at the New South Wales port fell $6.85 to $180.85 a metric ton in the week ended July 18, according to the globalCOAL NEWC Index. The price had reached a record $194.79 a ton in the week ended July 4.

Prices from the port have more than doubled this year on increased demand from Asian electricity producers and as railroad and port bottlenecks in Australia and South Africa curb supplies. Thermal coal producers won a 125 percent increase in annual contract prices in the year that started April 1 to $125 a ton.

Xstrata Plc, the world's largest exporter of power-station coal, BHP Billiton Ltd. and Rio Tinto Group are among mining companies that ship coal through Newcastle.