A strike by more than 160 Apache offshore workers could shut down critical North Sea platforms and disrupt nearly a third of the UK’s oil and gas pipeline, union leaders warned.

Unite said workers emphatically backed industrial action after rejecting a pay offer they called unacceptable. The union claims the deal amounts to a real-terms pay cut for many staff while Apache reported strong financial results. Unite general secretary Sharon Graham said: “We will not tolerate unacceptable pay offers.” Unite industrial officer Stevie Davies added that the walkout “would have a direct hit on the Forties pipeline and potentially severely affect the UK’s fuel supplies”.

Apache offered a 4% pay increase and stated that its workers are among the highest earners in the UK. The Texas-based APA Corporation reported $1.4bn (£1.1bn) in after-tax profits and $9.2bn in revenues last year. Apache said the offer matches increases given to non-unionised staff earlier this year and outlined contingency plans to keep experienced personnel on key sites. The company expects these measures to prevent impacts on other producers using the Forties pipeline system.

Fuel prices are already rising as the US-Israel war on Iran disrupts Gulf crude and refined oil supplies. On Friday, the average diesel price climbed to a record £2 a litre. G7 leaders will release up to 100m barrels of emergency diesel and crude oil stockpiles after Donald Trump threatened to cut off US diesel supplies. Unite warned that Apache’s industrial action could ripple out and affect other large North Sea operators.

Planned strikes by Neo Next offshore workers were called off this summer after securing a deal raising pay by more than £4,000. That agreement was reached days before strikes were scheduled to start on 22 July. Apache warned that strike action could begin later this month. Ineos, which operates the Forties pipeline system, was contacted for comment.