Richards Bay port manager Preston Khomo said work at the port had returned to normal.

It initially suspended operations on Monday after the Smart entered a swell estimated at 10 meters and went aground on a sandbar as it was leaving the harbor.

The 230m ship, carrying 147,650 tons of coal, was abandoned at about 4pm. Twenty-three on board were rescued, none with any serious injuries.

“Three salvage crew, one from the South African Maritime Safety Authority and two from marine services group Subtech, are on board the coal carrying ship MV Smart that ran aground yesterday afternoon to make an initial damage assessment,” the port’s statement said.

“Currently, there is no environmental impact. There is no oil spillage at this stage.”

Investigators believe the ship's engine may have failed, according to Reuters

The single-hull, 151,279 metric ton ship is registered to Alpha Marine.

The news service said the load of coal was going to a port in China, though the type of coal it was carrying was unknown.

Port authority officials said the vessel had broken apart with large portions under water.

“Tugs tried to assist the vessel but to no avail,” Transnet said.

“The vessel has buckled and broken in two."

The vessel was the second to run aground in the region in a month.

In early August, the 165m cargo ship Kiani Satu, which was carrying rice, was damaged in a similar incident off the southern coast.