Petro-Canada reached an agreement in principle with Montreal workers Friday. (CBC)

Petro-Canada has reached an agreement in principle with the union representing hundreds of locked-out workers at a Montreal refinery.

The 260 employees at the east-end facility have been off the job for 13 months.

The workers, who are members of the Communications, Energy and Paperworkers Union, have been without a contract since their previous deal expired on Jan. 31, 2007.

The union executive is recommending that its members accept the deal.

Daniel Cloutier, a national representative for the union, would not discuss the details of the agreement. But he said he was very satisfied a tentative deal could be reached. Many circumstances helped to unblock the negotiations, Cloutier said, primarily the appointment of former Quebec premier Lucien Bouchard as mediator at the beginning of the month.

At the start of the dispute, the union said it could not accept company demands to claw back seniority rights and change long-standing methods of bargaining.

The union voted in favour of a strike mandate, and the company eventually locked out workers in November 2007. Management began operating the facility instead.

Tensions between the two sides increased this fall when the union asked the public to boycott Petro-Canada fuel stations. The union had the support of the Canadian Labour Congress and Quebec Federation of Labour, the province's largest labour organization.

The employees will vote on the proposal on Dec. 22.