New Zealand's Bay of Plenty is forecast to experience another episode of harsh weather over the weekend, making salvors worry about the fate of MV Rena, which is still stuck on a reef despite being split in two on the surface. Maritime officials, however, said they are prepared for the worst.

A low pressure system near New Caledonia is predicted to shift southeast on Saturday, bringing winds up 50km/h to the area around the Rena, the New Zealand Herald reported.

In the event of ferocious weather, salvors on the shore would have at least 12 hours to prepare in case any amount of oil or debris reached Bay of Plenty beaches.

MetService weather ambassador Bob McDavitt said 3m to 4m-high waves could hit Rena several times an hour, which is akin to what the ill-fated ship suffered in the last week of December before it broke in two.

McDavitt added the highest waves could reach 7.5m, but it would be a once-a-day occurrence, if ever the weather gets really bad.

It remains unknown whether Rena is complete split under the surface, as the waters have not calmed enough for divers to take a good look.

Salvage unit manager Kenny Crawford told the Herald the split in the broken vessel had become too wide to sustain the weight of salvors, so they were constructing a temporary gangway between the two sections before a more permanent structure was built and the salvage operations on board continue.

As much as the salvors are prepared for the worst, the actions they would take still depends on the circumstances.

"If it breaks in half in seven-metre waves, are you going to put people in the way of danger? It's an assessment we'll make at that time," Crawford said.

National on-scene commander Alex van Wijngaarden also told the Herald the salvage crew will have to "wait and see."