A fresh oil leak from grounded container ship the Rena is projected to impact on Mayor Island, according to National on scene commander Rob Service.

About five to 10 tonnes of oil leaked from the Rena overnight, predicted to have escaped form the ship's duct keel (a tunnel running the length of the vessel that houses pipe work).

Sailors from Devonport in Auckland and Tauranga's 6th Hauraki were some of the hundreds of volunteers cleaning in Maketu and Mount Maunganui. Photo by Laura Weaser.

Rob says teams are monitoring the oil, tracking its trajectory and at this stage tidal direction indicates the oil will put Mayor Island at risk.

He says they are in the process of arranging a wildlife team to access the impact on the wildlife.

Two on water recovery operations were mobilised this morning, armed with booms and skimmers. While these methods are effective, there is still the possibility that oil will wash up on the shore.

Rob says as weather conditions are quite uncertain at this stage, the oil spill could quite easily shift direction.

At least 100 clean up volunteers were working hard at Waihau Bay, and 250 volunteers were on Mount Maunganui main beach, east of Leisure Island.

While the water and beach was opened to the public today, Rob says this is not indefinite and should the oil leak impact on the health and safety of beach goers, the beach will be closed again.