(Adds comment, detail)
* Agreement reached after talks extended for 3 hours
* Strike would have hit gas supplies to Britain
* Could also have harmed global LNG deliveries
OSLO, Oct 7 (Reuters) - Workers and employers at three plants serving Norway's energy industry agreed a wage deal early on Friday, avoiding a strike that could have cut gas supplies to Britain, the negotiators said.
The parties reached the agreement after extending talks for three hours past a midnight deadline. A strike could also have harmed deliveries of liquefied natural gas (LNG) worldwide,
"We are happy that the parties have agreed during the mediation on a new collective agreement for the next two years," said Jan Hodneland, a negotiator for the oil industry.
Altogether 338 members of the SAFE union were set to go on strike at Statoil's Melkoeya LNG plant, Shell's Nyhamna natural gas processing plant and ExxonMobil's Slagen refinery terminal if the wage talks had failed.
The Melkoeya plant turns gas from the Arctic Snoehvit field into LNG, while Nyhamna can supply up to 20 percent of Britain's natural gas demand from the giant Ormen Lange field offshore in Norway. (Reporting by Nerijus Adomaitis; Editing by Terje Solsvik and Joseph Radford)