Saudi Arabian Mining Co (Ma'aden) said its third-quarter net profit more than trebled on the back of contract receipts from a phosphate joint venture, which helped offset declines in its gold and other fertiliser businesses.

The firm made a net profit of SR1.43 billion ($381 million) in the three months to September 30, up from SR311 million in the same period last year, it said in a bourse filing.

Ma'aden attributed the rise in net profit to "the receipt of contractual dues from joint venture partners ... in the amount of SR1.44 billion" relating to its Waad Al Shamal phosphate project.

That project, being developed with Saudi Basic Industries Corp and Mosaic Company and estimated to be worth around SR26 billion, will also include an ammonia plant, and a train line from its remote location in northern Saudi Arabia to the industrial facilities on its Gulf coast.

Without the one-off gain, gross profit for the quarter fell 45 per cent to 396m riyals and its operating profit was down 80 per cent at SR98 million.

Ma'aden said the one-off boost helped offset a decline in gold prices, as well as a fall in prices and production.-Reuters