The condition of a cargo ship stranded on a New Zealand reef for nearly a month has worsened, and authorities say they are preparing for it to break apart.

Salvage crews have been in a stop-start race to remove oil from the vessel Rena to prevent it from leaking into the ocean. Crews removed more than 1,100 tons of oil before bad weather halted efforts on Sunday. About 385 tons remain on board about the same amount that has leaked into the sea.

The ship has been stranded since Oct. 5. The reef is about 14 miles (23 kilometres) from Tauranga Harbour on North Island.

Maritime New Zealand said on Tuesday a barge attached to the ship’s stern will drag the vessel to shallower water if it breaks apart.

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