Shanghai | One of China's biggest port operators has banned Australian coal shipments while exports of the commodity to other ports were facing delays of up to 45 days, according to traders and analysts who warn the move is politically motivated.

One coal trader in China told The Australian Financial Review that Dalian Ports Group, which oversees five key harbours in the country's north, had banned Australian coal imports completely. Reuters earlier quoted an unnamed official at the port saying that Australian coal had been blocked and it would cap total imports at 12 million tonnes. The report sent the Australian dollar down about one per cent.