North Sea offshore workers have gone on five days of industrial action over planned shift change patterns.
Unite members on the Dunbar, North Alwyn and Total Elgin started a 24-hour stoppage on Monday at 7am.
Four more planned stopages are pencilled in for 19 and 27 March and 2 and 12 April.
John Boland, Unite regional industrial officer, said: “There was an overwhelming mandate for this action by the membership which should have brought Aker and Petrofac back to the negotiating table.
“This is something they have refused to do so far and Unite will escalate our industrial action over the coming weeks causing widespread disruption until both Aker and Petrofac see sense.”
North Alwyn and Dunbar platforms voted 93.9% in favour of the strike action, and Elgin-Franklin platform members voted 88.2%.