The Unite trade union has criticised oil giant ExxonMobil as it shuttered its Mossmorran plant.

The Fife Ethylene Plant was due to close this month, but the union claimed it was shut down early, with production ending on Monday.

Exxon announced the impending closure last year, with around 400 jobs at risk as a result, claiming it was no longer financially viable.

No immediate job losses are expected as a result of the end of production on Monday, but it is understood 69 staff will leave at the end of April, with 90 remaining to complete the decommissioning of the site, who will then leave in three waves up until the expected completion in early 2028.

According to the firm, 20 staff have chosen to relocate to other parts of ExxonMobil’s UK operation.

Along with the firm’s own staff, around 250 contractors worked on the site.

In a statement, a spokesman for the company said: “After more than 40 years of operations, Fife Ethylene Plant permanently shut down production on February 2.

“In the months ahead the plant will be fully decommissioned and made safe for dismantling. We anticipate this process to be completed by early 2028.”

But the trade union hit out at the firm, claiming it had ended production early.

ExxonMobil had previously planned to close the plant on February 16, but it is understood an operational issue with a unit on the site, which would have required multiple days for repair and to restart, was the reason for the early closure.

Unite’s general secretary Sharon Graham said: “This is another nail in the coffin of the oil and gas industry, with jobs haemorrhaging on this government’s watch.

“Unite has said repeatedly that the government should not be letting go of one rope before it has hold of another.

“Importing oil and gas while we offshore our carbon responsibilities is quite frankly an abdication of responsibility which makes us more vulnerable and betrays workers.

“ExxonMobil’s decision to close Mossmorran ahead of schedule is a disgrace and a betrayal of its workers.

“This is an enormously profitable multi-billion pound company and this unnecessary decision will have a devastating impact on the local community in Fife.”

Deputy First Minister Kate Forbes said the news would be “difficult” for workers, but the Scottish Government was “doing all it can to support them”.

“I have written to worker representatives to assure them of our support and to ExxonMobil to ask that the workforce is prioritised,” she said.

“We have committed £9 million over three years to mitigate the impacts of the plant’s closure, with our Partnership Action for Continuing Employment providing skills and employability support to workers.

“This funding will also support the site’s long-term future, with Scottish Enterprise identifying new investment opportunities.”

Scottish Tory business spokesman Murdo Fraser said the closure was a “terrible blow” for the area and the workers.

“As with Grangemouth, the SNP government promised swift action to protect workers and the local community, but their task force didn’t even meet until last week,” he said.

“These closures are the inevitable result of Labour and the SNP having created a hostile environment for businesses, especially those connected with the oil and gas sector, by piling on punitive taxes and regulations.

“Ministers must now ensure that there is decisive action to support those affected, and not merely empty promises.”

The Directorate General of Civil Aviation (DGCA) said on Tuesday that when the switches were operated according to Boeing’s recommended procedure, they were found to be “satisfactory”, staying at run instead of moving to cut-off (which can stop fuel supply to the engines).