The stern of a broken-up ship that caused New Zealand's biggest sea pollution disaster sank on Wednesday after waves of up to 12 metres (39 foot) pounded the wreck, officials said. The Liberian-flagged Rena ploughed into a reef on October 5, releasing an oil slick that killed thousands of sea birds and fouled beaches in the North Island's pristine Bay of Plenty.
The ship had been lodged in two pieces on the reef with about 75 percent of the stern under water, before the rest slipped in on Wednesday. Maritime New Zealand (MNZ) said the latest development had created a "light" oil slick one kilometre (0.6 miles) long and warned locals there was a risk pollution could wash up on the shore.