North Sea oil construction workers staged 24-hour strikes on 14 platforms on Monday 19 June.
A strike across the whole North Sea oilfield has been called for 6 July - the anniversary of the Piper Alpha disaster which killed 167 people.
There has been a series of unofficial strikes and work to rules in the past three weeks. Acion is organised similarly to the London Tube strikes, by semi-clandestine rank and file 'liaison committees', with the tacit support of union officials.
Contract workers want guaranteed pay and conditions under the Offshore Construction Agreement. At present bosses cancel the agreement when rigs hook up and begin oil production.
They want union safety reps' inclusion under Health and Safety legislation, and the Health and Safety Executive (instead of the Department of Energy) to monitor safety. There are also calls for a single industry-wide union.
Most contruction workers are employed by contractors, on worse conditions than permanent staff and up to £100 a week less pay. But all workers across the industry are increasingly angry over pay, conditions, and safety.