Offshore workers in the North Sea have gone on the first of five days of industrial action amid a dispute over planned changes to shift patterns.
Unite members on the Total Elgin, North Alwyn and Dunbar platforms started a 24-hour stoppage at 7am on Monday.
A further four stoppages are pencilled in for March 19 and 27 and April 2 and 12.
Aker and Petrofac previously proposed a change to the on-off shift rotation from two weeks on, three weeks off to a three-three and three-four basis.
A reduction to the existing terms and conditions from parent company Total is also part of the grievances.
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.”
Elgin-Franklin platform members voted 88.2% in favour for industrial action and on the North Alwyn and Dunbar platforms it was 93.9%.
A spokesman for Aker Solutions said: “We remain in close dialogue with the trade unions, our employees and our customer throughout this period of consultation and have now issued our employees with revised terms and conditions, which reflect a salary enhancement, in an attempt to bring this to resolution.
“The safety and wellbeing of our people remains our top priority.
“We will continue to work closely with all parties to ensure this process is brought to conclusion as efficiently and fairly as possible.”