Auckland Coastguard apologises after dashing to fetch tonic water for luxury launch, says it was offered $100

The Auckland Coastguard has apologised after it made a mercy dash at the weekend - for tonic water.

Coastguard says it was offered $100 to ferry a case of tonic water to a charter vessel off Waiheke Island.

While there was no risk to anyone and no other tasks at the time, Coastguard says it wasn't the right use for the vessel and the crew will be formally debriefed.

Despite being a charity, Coastguard New Zealand says it won't accept the $100 donation.