South Africa posted a trade surplus in September, the largest since December 2003, as mineral exports surged and the first recession in 17 years curbed oil imports. The 3.9 billion-rand ($499 million) surplus compared with a 1.98 billion-rand deficit in August.

“The decline in South African imports, due to the recession, and modest improvement in exports, helped by some improvement in the global economy, has meant that South Africa’s trade balance has recorded a very noticeable and welcome improvement,” Kevin Lings, an economist at Stanlib Asset Management, said in a note to clients. This should “be sustained during the remainder of 2009 and into the early part of 2010.”

The price of gold surged 6 percent last month while platinum, which vies with gold as South Africa’s biggest export, advanced 4.8 percent as a drop in the value of the dollar boosted demand for alternative investments.

Rising metal prices bolstered the rand, which gained 3.4 percent against the dollar last month, reducing the cost of oil imports. Demand for oil was also curbed by the recession, which has seen manufacturers and miners cut production and fire staff.