Interislander ferry sailings could be suspended for a week next month after the unions representing more than 100 crew announced a strike over pay rates.
The KiwiRail-owned ferry company said both the Aviation and Marine Engineers Association and Merchant Services Guild issued strike notices yesterday.
The notices come after several months of collective agreement negotiations failed to reach an agreement on pay rates.
Interislander general manager Thomas Davis said the strike would suspend all Interislander sailings from December 1 to 7.
"Interislander remains committed to a speedy resolution and will continue to negotiate with both unions with a view to reaching settlement before the strike period begins.''
A notice on the Interislander website warns sailings could potentially be disrupted.
The website said it was a precautionary notice only and the company was optimistic there would be a "quick and positive resolution'' with no interruption of services.