The Grangemouth petrochemical plant in Scotland is to stay open after a new deal was struck with the workers’ union, Unite.

Workers were told in a meeting at 11:00 that the decision to close the site would be reversed.

On Wednesday the owner Ineos announced that the petrochemical plant would be liquidated, after workers rejected a survival plan, and there were concerns for the fuel refinery that is on the same site. Ineos chairman and founder Jim Ratcliffe had said at the weekend that if the petrochemical plant closed it was likely the refinery would go as well.

In a statement, Ineos said it would reopen its petrochemicals business and the neighbouring oil refinery with immediate effect.

The company said the move had followed a “dramatic U-turn” by the union Unite and its “belated recognition” that the company’s survival plan was the only way to ensure Grangemouth’s long-term survival.

It added that Unite had agreed to taking no strike action for three years, moving to a “modern” pension scheme and a three-year pay freeze.

It said: “The Scottish government has indicated it will support the company’s application for a £9m grant to help finance a new terminal and the UK government has given its prequalification approval for a £125m loan guarantee facility.”

Pat Rafferty, Unite Scottish secretary, said: “This decision is clearly very welcome. Relief will ring right round the Grangemouth community, and across Scotland today. Hundreds of jobs that would have been lost can now be saved and £300m will be invested into the plant.

“Grangemouth is the powerhouse of the Scottish economy - it now has a fighting chance of upholding this crucial role into the future.

“Obviously today’s news is tinged with sadness - decent men and women are being asked to make sacrifices to hold onto their jobs, but the clear wish of our members is that we work with the company to implement its proposals.

“Unite has worked tirelessly to save Grangemouth because we are totally committed to this plant and its incredible workforce. We will now sit down with Ineos to consult on the company’s proposals.”

Secretary of State for Energy and Climate Change Edward Davey commented: “This is a very positive result. Grangemouth is important to the Scottish economy, the UK economy and most importantly to the local economy where 800 jobs have been saved and the local community has avoided a major blow. We can now look forward to a future of growth at Grangemouth.

“Many people in the UK and Scottish Governments have worked hard to make this happen, a clear sign of our commitment to Scotland, its economy and its people.”