An aerial observation flight this morning has confirmed oil leaking from the cargo vessel grounded on a reef near Tauranga Harbour has led to a light oil slick.
The MV Rena is at the centre of a big salvage and environmental management effort since is struck the Astrolabe Reef north of Motiti Island about 2.20am yesterday.
Dangerous items were understood to be aboard the container ship - this morning that was confirmed as an alloy used in making steel.
The National Response Team was advised of the leak during pumping operations around 10pm last night, and plans were put in place overnight to prepare for an early morning response.
The National On-Scene Commander, Rob Service, said the flight this morning had confirmed a slick of thinly spread oil streaming around 2000 metres in a narrow strip from the ship.
"The oil is very thin and it appears it is starting to break up and disperse naturally," Mr Service said.