Svitzer salvors are planning how to remove a container carrying ferrosilicon from the Rena wreck at the Astrolabe Reef.

Maritime New Zealand is reporting the container was ‘wet-stored' in 9m of water at the weekend after salvors detected higher than normal gas levels emanating from it.

Containers can be seen pushing open the hatch covers on the bow section of the Rena wreck. Photo: LOC.

When the ship ran aground at the reef on October 5, there were eight containers onboard containing a toxic substance; four of these held ferrosilicon.

It is a hazardous substance that is flammable when combined with fresh water.

Securing this container was just one task undertaken by the salvors at the weekend, who also removed eight and a half containers from the sunken stern section.

The removal operation continues to be undertaken by the Smit Borneo crane barge.

It is secured to the port quarter of Rena by wire ropes.

Salvors are today focusing on removing formerly refrigerated containers and cutting them up as required.

One such container was cut at the weekend by salvors working from the Smit Borneo barge.

The container held 53 big bags of lamb.

The container scrap and its spoiled cargo were then discharged to the Sea Tow 60 barge.

So far 544 containers have been retrieved from the decks of Rena and brought ashore, along with another 70 from the sea and beaches.

Patches of debris are also seen to be floating and on Sunday two skips worth of blue twine was collected from the sea between Waihi Beach and Mayor Island.

A helicopter was used to locate the floating twine for its collection by a fast response vessel and barge.

Weather conditions at the wreck site are forecast to deteriorate with light variable winds this morning, rising to 16 knots this afternoon and increasing to 20-25 knot northerlies on Wednesday.

The strengthening northerly wind is forecast to elevate the sea state through Wednesday with about 2m significant wave heights expected on Wednesday afternoon and Thursday morning.