Global miner Anglo American has declared force majeure on its coal mines in Australia's Queensland state due to prolonged heavy rains, joining a long list of coal firms suffering from weather related problems.

"Adverse impacts due to flooding vary across our operations and include disruption to road access, production and rail transportation," the company said on Thursday.

"The full impact is not clear as rain continues to fall, with further rain forecast for the region," Anglo American said.

Anglo American is the latest to report difficulties after global miner Rio Tinto [RTP 60.45 --- UNCH (0) ] , port operators Dalrymple Bay Coal terminal and Gladstone Ports, and rail firm QR National all said on Wednesday that weather related problems are forcing them to slow or halt operations.

Australia is the world's biggest exporter of coking coal used for steel-making and accounts for about two-thirds of global trade. The nation is also the second-biggest exporter of thermal coal used for power generation after Indonesia, with about 20 percent of world exports.

The country's unusually wet spring and early summer have already pushed both coking coal and thermal prices sharply higher and tight markets are keeping a close eye on further disruptions.

Queensland produces mostly coking coal which is exported to be used in steel-making, but some mines also produce thermal coal used in power generation. Queensland's ports currently have an annual coal export capacity of 225 million tonnes per year.

Anglo American is the second-largest exporter of metallurgical coal in Australia and owns two thermal coal mines.

Its mines affected are Callide, Dawson, Foxleigh, German Creek and Moranbah North, the company said in a statement.