The 18-day Transnet strike in May prevented exporters from shipping their goods on time, with the consequence that June's trade data were artificially boosted by the resumption of services in June.

The strike led to a backlog and stacking of goods in June when the strike ended.

The backlog resulted in a sudden and unexpected surge in the foreign trade surplus in June of R5.629-billion.

Exports were shown to have increased by 17.8% in the month to R55.6-billion, and imports rose 5.2% to R49.9-billion.

On the year, exports are up 7.3% to R272.4-billion, and imports are up 3.2% to R280.2-billion.

The rand, despite the artificial nature of the June reading, pulled off its weak levels of over 7.30 to the dollar largely because of the widespread perception that the economy is benefiting from an export-led recovery.

It is indicative of the growing demand for South African goods from offshore, a good sign when it comes to economic growth, running at 4.6% in the first quarter.

The export performance is backed up by the year-to-date ports data to June at 128.5 million tons from 114million tons at the same time a year ago - up 12.50% from 11.90% in May.

"The surplus is mainly due to base metal and foodstuff exports," said Loshnee Naidoo, manager of SARS's customs department.

It follows a deficit of R302-million in May.