Tomorrow the salvage operation on board the wreck of the cargo ship Rena will shift from pumping off oil to removing containers.

Transport Minister Steven Joyce today told media removing containers from the Rena will take months.

About 1300 containers are on ship and it is estimated a maximum of six containers will be able to be moved a day.

"While there is still a long, hard road ahead, the first priority has always been the safe removal of oil from the Rena and it is a huge relief to everyone involved that that has largely now occurred," he said.

The shipping company that owns Rena has been told they must remove the vessel once work is complete, however it was still possible the ship could split up, said Joyce.

There was a "strong possibility" that some oil remained trapped on the vessel which could be released if it broke up.

MNZ Salvage Unit Manager Arthur Jobard said there was around 60 tonnes of oil remaining in the starboard number 5 tank, with 319 tonnes pumped off. This could be done along side container removal.

The bulk of the heavy fuel had been removed from the ship and pumped into oil tanker Awanuia, which today returned to the Port of Tauranga.

Taking its place will be crane barge Sea Tow 60 which will leave the Port of Tauranga tomorrow and position itself alongside the Rena.

BEACH CLEAN-UP

It was hoped that some beaches would be opened to the public this weekend, but they will remain closed for at several more days, Maritime New Zealand said.

Beach restrictions remain in place from Tay Street in Mt Maunganui to Maketu.

National On Scene Commander Rob Service said that more surveys and consultation with "key parties" was needed before further beach access would be granted.

"We know people want to get onto some of those beaches, but we can't rush in - we must ensure we have worked carefully through that process."

There was still a significant amount of oil in the sand and on rocky shorelines. Clean-up teams would be focussing on Matakana and Rabbit Islands, and at Mount Maunganui, Papamoa and Maketu today.

Service said those who were clearing oil from the beaches were heartened by the progress salvors had made on board the Rena.

"It's great news for us that we are getting closer to the point where the risk of another significant spill from Rena is gone."

The cost of the response so far is about $12 million.