Despite stalled container removal operations from the Rena, Maritime New Zealand is happy with progress being made in the ship's salvage.

MNZ salvage unit manager Arthur Jobard says salvors have focused on structural works onboard the vessel stranded on the Astrolabe Reef since October 5.

Rena's stern deck is clear of containers. Photo: MNZ.

'Salvors have focused on work onboard Rena and have installed patches in the corridors of the wreck – this will enhance buoyancy.

'We have also this week seen the arrival of the crane barge Smit Borneo.

'This has a much greater reach and capacity than the Sea Tow 60, which will enable salvors to remove containers currently out of reach.

'However, it's important to emphasise that the weather will continue to play a huge part in this operation.

'Smit Borneo will be affected by swells and wind in the same way the Sea Tow 60 was.

'Safety remains the number one priority and salvage operations will only be undertaken when it is safe to do so.”

MNZ national on scene commander Mick Courtnell says the oil spill response team is continuing to monitor the sheen around Rena.

'We have seen a little more oil leak from Rena with the variable winds and high swells.

'This has resulted in some sticky tar balls coming ashore and we have had a number of reports from members of the public.

'We appreciate this is frustrating for people, particularly with summer almost upon us.

'Unfortunately, there is still a reasonably significant amount of oil on the wreck, out of reach of salvors.

'There is also still residual oil in the water, some of which is floating below the surface, and in the sand. This oil gets moved around with changes in the weather.

'Our teams will continue to clean and re-clean these beaches as long as we need to.”

Mick says responders are starting to notice algal blooms, which are usually prevalent at this time of year. These could sometimes be mistaken for oil in the water.