UPDATED: The 20 metre fishing vessel that ran aground on Red Mercury Island, 30km off Whitianga, has been re-floated.

With Waikato Regional Council craft and fuel-containment booms standing by on site, the vessel's crew was able to use an anchor and winch during high tide to haul it off the rocks where it became stuck overnight.

This picture shows the vessel before it was re-floated.

No fuel went into the sea during the grounding and re-floating.

'This is a great outcome considering the risk of some of the 9000 litres of diesel aboard getting into the sea,” says the council's regional on-scene commander Dave Lovatt.

'The vessel that was grounded is now safely back at sea and there have been no injuries to the crew. This is a great outcome to a potentially risky situation.”

Exactly why the vessel grounded has still to be determined, says Dave.

At 3am, the council had formally declared a tier 2 regional marine oil spill response to help it manage the situation as efforts were made to refloat the boat and to deal with any fuel that might leak.

An incident control centre was activated in Hamilton.

'We take any grounding like this very seriously in terms of the risk to the environment. We're happy the situation has been successfully resolved and our staff and equipment are now being stood down.

"The crew was cooperative and had carried out a successful salvage."

Earlier:

A 20 metre fishing boat with three men on board is aground on Red Mercury Island, off the Coromandel coast today.

There are no injuries and the boat is believed to be unholed.

Regional marine oil spill responders and equipment have been deployed as a precaution in case the 9000 litres of diesel begins to leak out of the vessel. File photo.

An attempt will be made to tow it clear on the high tide at about 11am.

The boat ran aground 30 kilometres off Whitianga on the southern end of Red Mercury Island.

The vessel, which is carrying about 9000 litres of diesel, appears intact and there is no sign of fuel having spilled into the sea at this stage.

The Waikato Regional Council formally declared a tier 2 regional marine oil spill response to help it manage the situation as efforts are made to re-float the boat and to deal with any fuel that might leak.

An incident control centre has been activated in Hamilton.

The fishing boat is on rocks on the southern side of Red Mercury Island.

Regional on-scene commander Dave Lovatt, from the council's regional hazards team, says the crew is safe and the sea and weather conditions are generally calm.

The skipper of the boat has deployed a support vessel from Tauranga to attempt to re-float the grounded vessel at high tide.

In the meantime, regional marine oil spill responders and equipment have been deployed from the council's Gordonton depot, and a harbourmaster is inspecting the vessel this morning to help inform forward planning and response options.

'We are hopeful of a quick and safe resolution to this situation but we are on standby and prepared to help if problems develop and any fuel leaks into the sea,” says Dave.

'We are moving equipment and staff into the area and will respond as required.”

Waikato Regional Council helping out after fishing boat grounds off Coromandel coast. No sign of fuel leak for now. https://t.co/dBlry3jPAW

— Waikato Regional Cou (@ourwaikato) May 11, 2016