Thermal coal prices at Australia's Newcastle port, a benchmark for Asia, were little changed last week as supply constraints at a storm-affected port in Vietnam offset declines in the price of oil.

The weekly index for power-station coal prices at the New South Wales state port fell 26 cents, or 0.2 percent, to $161.89 a metric ton in the week ended Aug. 29, according to the globalCOAL NEWC Index.

Prices may remain at similar levels in the coming months as supply constraints are offset by a weaker oil price, Mark Pervan, senior commodity analyst at ANZ in Melbourne, said in an Aug. 26 report. Storm damage at the port of Cam Cha port in Vietnam, the largest supplier of power-station coal to China, cut shipments from the port by about 13 percent last month, Macquarie Group Ltd. said in a report today, while oil prices fell 7 percent last month.

The weekly globalCOAL index is up 80 percent so far this year and rose to a record $194.79 a ton in the week ended July 4. The monthly index fell 13 percent to $160.90 a ton in August, from $184.51 the previous month.

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.