The operators of French Polynesia's new King Tamatoa fast ferry say they will pull out of the territory if the government reneges on the tax exemption promised to them.
The shipping company says it will stop running its service to the Society islands from Wednesday local time.
It says if the tax exemption is not approved by the end of June, the vessel, which had been brought from France, will leave.
There was controversy when the fast ferry service was mooted last year, with all shipping briefly stopped in protest.
But after negotiations, the service was launched in April.