By Nerijus Adomaitis
OSLO (Reuters) -At least 647 Norwegian oil workers plan to strike from June 12 if state-brokered wage mediation fails, labour unions said on Friday, putting some crude output at risk of shutdown although gas may not be affected.
Workers are seeking above-inflation pay increases and other changes to their contracts but have not released details of their demands.
Members of the Industri Energi and Lederne unions plan strike action at 10 permanent offshore installations, including the Njord A, Valhall, Gudrun and several Oseberg platforms, as well as three mobile service units, the unions said.
Lederne would initially involve 74 mostly senior offshore workers in a strike, likely hitting oil production at the Equinor-operated Gudrun, Oseberg South and Oseberg East platforms, the union said.
Gas production should remain unaffected however, Lederne chief Audun Ingvartsen told Reuters.
"We will try to avoid affecting gas production as we are mindful about the situation with gas supplies in Europe," he said.
"I hope we can find the best solution both for Norway and the oil companies, and at the same time give something back to the workers. I hope we can avoid a strike."
Lederne is negotiating on behalf of some 1,300 union members.
Equinor did not immediately respond to a request for comment.
Gudrun produced 45,700 barrels of oil equivalent per day (boed) in 2021, Oseberg East 5,600 boed and Oseberg South 32,000 boed, official data shows, around two percent of Norway's overall daily oil and gas output.
The Industri Energi union meanwhile said it would initially seek to avoid hitting production altogether, even as 573 of its members could go on strike.
"The first instance of a potential strike would only involve a limited number of members, but we can escalate if necessary," Industri Energi's chief negotiator Lill-Heidi Bakkerud said.
Industri Energi is Norway's biggest oil and gas union, negotiating on behalf of some 4,300 members.
The Safe labour union, which will also take part in the June 10-11 mediation, has yet to outline its response.
(Additional reporting by Nora Buli, editing by Terje Solsvik, Kirsten Donovan)