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OSLO, Oct 3 (Reuters) - Workers at three onshore plants serving Norway's oil and gas industry will strike from Oct. 7 unless they get a new wage deal, the SAFE labour union said on Monday, potentially threatening Britain's natural gas supplies.
Some 338 workers at Statoil's Melkoeya LNG plant, Shell's Nyhamna natural gas processing plant and ExxonMobil's Slagen refinery terminal would go on strike if talks on a new pay deal break down, the union said.
The Melkoeya plant turns gas from the Arctic Snoehvit field into liquefied natural gas (LNG) which is shipped worldwide, while Nyhamna supplies about 20 percent of Britain's natural gas demand from the giant Ormen Lange field offshore Norway.
"The onshore facilities would shut down, and would stop receiving both oil and gas," union official Roy Aleksandersen told Reuters.
Shell and Statoil both said they were studying the impact of a strike.
"We're awaiting the outcome of the mediation and are considering internally what the consequences of a potential strike could be," a Shell spokeswoman said.
"We are working to assess which consequences this potentially could have for us," said a Statoil spokeswoman who declined to comment further.
ExxonMobil was not immediately available for comment.
The negotiations will take place on Oct. 6. (Reporting by Stine Jacobsen, writing by Terje Solsvik, editing by Nerijus Adomaitis and Jane Merriman)