Salvors working on the Rena have started removing pre-cut scrap metal with a helicopter and crane.

The Rena has been sitting on the Astrolabe Reef since it crashed on October 5 last year, causing an environmental disaster when oil began to spew into the sea.

The condition of the wreck deteriorated and on January 10, the ship snapped in half with much of the stern resting under water.

After months of moving containers ashore attention shifted in June towards removing the wreck.

The ship's owners and insurers appointed a US-based company, Resolve, to reduce the size of the bow to one metre below the water line.

Salvors began cutting through the internal structure last week, and today began to remove the scrap metal. The project is expected to be completed early 2013, depending on weather conditions.

"This is a difficult and potentially dangerous location to conduct salvage operations," Captain John Owen, senior claims manager for insurers The Swedish Club who is overseeing the wreck recovery project, said.

"However, we are confident Resolve will complete the project safely and to the satisfaction of the Bay of Plenty community."

A helicopter will be extensively used as the bow section is surrounded by shallow water, inhibiting the use of a heavy lift barge.

It will remove steel from the forward section, while a crane barge will work from the deeper water.

The shell plating and ballast tanks will be left until the final phase of the project to act as a breakwater.

Once all the major internal structures are removed, the shell plating will be removed to one metre below the waterline.

An underwater survey will then be completed to make sure the work has been done properly.

- © Fairfax NZ News