Two Vermont utilities have reached agreement on a deal to buy power from Canadian provincial utility Hydro-Quebec, replacing contracts that expire beginning in 2015.

The deal is among Green Mountain Power Corp., Central Vermont Public Service Corp. and Montreal-based Hydro-Quebec, which already provides about one-third of Vermont’s electricity.

Details weren’t immediately available. A news conference was planned Thursday in Quebec City, Quebec, where Vermont Gov. James Douglas and Quebec Premier Jean Charest have been meeting in a trade mission.

Robert Dostis, a spokesman for Colchester-based Green Mountain Power, confirmed early today that a deal had been reached but would not give details.

Steve Costello, a spokesman for Rutland-based Central Vermont Public Service Corp., declined to comment except to say that Douglas, Charest and representatives of the three utilities would hold the news conference.

The Vermont utilities have been negotiating with Hydro-Quebec for over a year in hopes of reaching new contracts, but the issue has gained urgency in light of recent developments at Vermont Yankee nuclear power plant.

The plant, which reported a leak of radioactive tritium Jan. 7 that has yet to be stopped, is scheduled to close when its license expires in 2012, although owner Entergy Corp. has applied for a 20-year extension.

Vermont’s state Senate voted Feb. 24 to close the plant in 2012, but that vote isn’t binding by itself.