The locomotives - 20 2250-class GT22CU-3 and 14 GL26C-2 locomotives - were loaded in Brisbane this week for shipping to Durban, South Africa.

The implications of the deal are that Transnet has a locomotive shortage and is looking for a quick fix.

A Transnet Freight Rail spokesman said 14 of the locomotives had been bought for "a specific operation" and would be based in Bloemfontein, while others would be deployed to certain branch lines.

The remaining 20 were bought by Transnet Engineering and will be used by TFR until the end of the financial year "to increase capacity in some areas", a Transnet Freight Rail spokesman said.

"Locomotives are the current constraint," he said. "But with their low axle load, these locomotives could also be directed to some of TFR's branch lines."

The 110-tonne GT22CU-3 locomotives are relatively new, having been rebuilt in the past 10 years and were in use until recently. The older GL26C-2 units were rebuilt in the 1990s. At 93 - 97.5 tonnes each, these are the most likely candidates for use on TFR's lightly-laid branches.

While former-QR locomotives have been sold in earlier deals to private South African rail and locomotive-hire operators, this is the first such deal involving Transnet.

The company is in the middle of a vast fleet renewal programme which will see it buy 1064 diesel and electric locomotives as part of its Rand 308bn market demand strategy.

Once the new-build locomotives begin to arrive, the ex-QR locomotives are likely to find work elsewhere in Africa.

"In the longer scheme of things TFR will supply some of these into Africa once the fleet renewal has reached a point where these are no longer required," the Transnet spokesman said.