Timaru's port company is to lose all its container work after shipping lines Maersk and Hamburg Sud today advised they were withdrawing their combined service in mid-September.

The Rail and Maritime Transport Union says the move is expected to mean the loss of more than 50 jobs.

PrimePort chief executive Jeremy Boys confirmed it would mean the loss of a container port in the South Island.

"This is the only container service into Timaru and although the Port is at the epicentre of the South Island's trade with perhaps the most direct logistics, it is difficult to see that the container business can continue or be put into a holding scenario without ships calling."

While the outcome would not impede PrimePort’s direction as a breakbulk port, Mr Boys said it was staff and many service providers who would bear the brunt of the announcement.

Rail and Maritime Transport Union organiser John Kerr told Radio New Zealand that staff had no idea before the announcement this morning that the shipping lines were pulling out.

He said 90 per cent of PrimePort's operations staff are involved in container handling and expected more than 50 jobs to be lost.

The decision was devastating for the workers and will have a massive impact on Timaru, Kerr told RNZ.

After September, the containers would be offloaded at Port Chalmers in Dunedin and sent to Timaru by rail, he said.

PrimePort employs 55 permanent and 30 casual staff.

- © Fairfax NZ News