Kiwirail says passenger sailings on the Aratere Interislander ferry have been cancelled until further notice.
The Aratere has had a number of serious problems since its $53 million refit in Singapore in April.
It limped into Wellington after trouble with its engines in Cook Strait last Monday and had more mechanical problems during sea trials on Wednesday.
Maritime New Zealand subsequently imposed a ban on all passenger sailings although freight sailings have continued since Friday night.
Kiwirail says it had hoped passenger sailings would resume on Tuesday but it now expects the ban will remain in place for at least the rest of the week.