A fishing boat that ran aground on rocks near Whitianga with nine thousand litres of diesel on board this morning, has been successfully re-floated.

There were fears the diesel might spill into the water and emergency crews were on standby for a clean up.

It was grounded near Red Mercury Island, well-known for its delicate wildlife.

The Waikato Regional Council said it took just half an hour to get the boat off the rocks - without a spill.

Crews were able to use an anchor and winch during high tide to haul the vessel off the rocks.