Bluebridge owner StraitNZ has confirmed its ferry the Connemara lost power in the Cook Strait last month because of contaminated fuel.
RNZ this week revealed fuel problems were the likely cause] of the Connemara's power loss, leaving it drifting for more than two hours and needing a rescue from tug boats.
Until Friday, StraitNZ had not commented on the cause, citing the ongoing Maritime NZ investigation.
But the Ministry of Business, Innovation and Employment, Maritime NZ, and Transport Minister Simeon Brown all confirmed StraitNZ had advised fuel issues might have been a contributing factor.
Until now, it has been unclear what exactly the fuel problem was - but in a statement, StraitNZ chief executive Shane McMahon confirmed the fuel was "contaminated".
The contaminated fuel damaged the ship's fuel injectors which caused the loss of power, he said.
The injectors had been repaired and the contamination had been cleared with the use of a biocide additive.
Investigations into how and where the fuel was contaminated are ongoing, and StraitNZ was working with authorities and its fuel supplier to determine the source of the contamination, McMahon said.
"Samples of fuel taken from the ship and its fuel supply since the 19 September incident have shown no contamination," McMahon said.