Eastern Quebec drivers seeking to cross the St. Lawrence River will have to take an 800-kilometre detour until next week after mechanical issues forced the suspension of ferry service.

The two ferries linking communities on the north and south shores of St. Lawrence east of Quebec City were out of service as of Thursday, forcing drivers to make the long trek.

The NM F.-A.-Gauthier running between Matane in Gaspe and Baie-Comeau and Godbout on the north shore has been out of commission since Dec. 17 because of a mechanical problem. The disabled ferry is just three years old.

The NM Trans-Saint-Laurent, linking Riviere-du-Loup on the south shore with St-Simeon in the Charlevoix region, ended its season Wednesday. Service on that route does not resume until April, but the ship needs to undergo repairs in Quebec City and is not available to replace the NM F.-A.-Gauthier.

A charter air service has been put in place for ferry users in the Gaspe and Baie-Comeau regions, charging the same fare but leaving users without their vehicles when they reach the other side.

The Crown corporation that oversees ferry service in Quebec said no replacement vessel was available before next Tuesday, when service is expected to resume.

Quebec Transport Minister Francois Bonnardel has previously been critical of the Crown corporation -- the Societe des traversiers du Quebec -- for failing to find a solution to prevent the interruption of service.

Aside from the inconvenience for commuters, companies that transport goods from one shore to the other say an interruption will come at a high cost.