Thieves have stolen the "lifeblood" of a Banks Peninsula volunteer Fire station.

Almost 300 litres of diesel has been stolen from the Diamond Harbour fire station.

Chief station officer Bob Palmer says they're gutted someone smashed the padlock on the diesel tanker and siphoned the fuel.

He said it was "quite a significant amount for us."

"We use that stuff obviously to fuel our firetruck, and our ambulance, it's sort of the life blood of our equipment."

Bob Palmer says the theft would have hampered their efforts to fight a large fire, because they had to get diesel trucked in from Christchurch.

He says they have no idea how the thieves managed to cart off such a large amount of diesel.