Rough weather in Tauranga has stirred up old oil from the grounded container ship, Rena, and it's being washed up on the region's beaches.
Tar balls are reported to have been found on beaches between Papamoa and Mount Maunganui.
The Shoreline Clean-up Assessment Teams are at the beaches, following up on the reports and the public have been advised the oil is not from a new spill.
The same rough weather has also forced salvors to stop removing containers from the vessel.
On Friday, a total of 166 containers had been successfully removed from the ship, with more than 1100 still on board.