Maritime New Zealand warns that more oil from the stranded container ship Rena will start washing up on Bay of Plenty beaches over the next two days.
The vessel ran aground on the Astrolabe reef off the coast of Mt Maunganui more than three weeks ago.
Maritime New Zealand's on-scene commander, Nick Quinn, said on Saturday that small amounts of oil seep out of the ship daily and a forecast northeasterly will wash fresh oil onto Papamoa beach over the next 48 hours.
Mr Quinn says some of the five to 10 tonnes that leaked last weekend is also expected to come ashore.
He says about 200 volunteers responded to the call for help in cleaning up the beaches on Saturday and he hopes even more come out on Sunday.
Meanwhile, salvage workers have again been pumping oil off the ship, after a four-hour halt early on Saturday morning when water was found in the tanks.