"The improvement in the trade account reflects a sharp decline in imports, mostly machinery and equipment as well as vehicles. In contrast, exports remained relatively unchanged despite some decline in precious metal exports, which probably relates to the recent strike in the platinum mining sector," Kevin Lings, chief economist at Stanlib, said in a statement.
The R6.57 billion deficit for May includes trade with Botswana, Lesotho, Namibia and Swaziland.
Exports increased from April to May by R0.45 billion, and imports decreased from April to May by R5.37 billion.
Precious metals and stones decreased by R2.1 million, and vehicles and transports equipment decreased by R1.2 million. Mineral products increased by one million rand.
Vegetable products increased by R618 million, machinery and electronics increased by R573 million, and wood, pulp and paper increased by R436 million.
"The April to May change in imports of goods is mainly reflected in [the] vehicles and transport equipment decrease by R2.1 million, [and the] machinery and electronics decrease by R1.7 million rand," the South African Revenue Service said in a statement.
The decrease in chemical products by R922 million also contributed to the change.
"Trade statistics with Botswana, Lesotho, Namibia and Swaziland for May 2014 recorded a trade surplus of R8.99 billion. The R8.99 billion surplus for May 2014 can be attributed to exports of R10.83 billion and imports of R1.84 billion," SARS explained.
"Exports increased from April to May by R1.23 billion and imports decreased from April to May by R0.36 billion. The cumulative surplus for 2014 is R41.64 billion compared to R32.65 billion in 2013."