Workers at a giant oil refinery and petrochemical site are to strike in a row over a union convenor.
Unite said its members at Grangemouth in Scotland will walk out for 48 hours from 7am on 0ctober 20 over the treatment of Stephen Deans.
The site's owner Ineos has launched an internal investigation into Mr Deans, who was involved in the dispute over the selection of a Labour candidate in Falkirk.
Mr Deans, who is chairman of Labour's constituency party, was suspended by Ineos, then reinstated.
Unite accused Ineos of refusing to take the dispute to the conciliation service.
Unite's Scottish secretary Pat Rafferty said: "Unite has made every effort to pull Ineos back from the brink but at every opportunity this company has kicked our proposals for peace into touch.
"We have pleaded with Government ministers in Westminster and Holyrood and the joint owners of the Grangemouth refinery Petrochina to help rein in this reckless company before it's too late.
"A damaging strike may shut down the Grangemouth site, with serious ramifications for fuel production and supply throughout Scotland and the north of England."
Ineos recently launched a survival plan for Grangemouth, warning that the site will close by 2017 without investment and reduced costs.
The company said it was losing £10 million a month.
Officials said the investigation into Mr Deans will be completed by October 25.
Unite received an overwhelming mandate for strike action from the workforce, with 81.4% voting for walkouts and 90% for other forms of industrial action, on an 86% turnout.
A work to rule and overtime ban has been in place this week.
Mr Rafferty added: "The company can level whatever accusations it wants to at Unite and our members but we can only interpret their actions as a sign that they are determined to see strike action in an attempt to break the back of our union and run Grangemouth into the ground.
"Unite will fight back against attacks on our union and any attempt to impose devastating cuts on our members' jobs and hard-fought terms and conditions because that's what strong trade unions do.
"We will not negotiate with a gun to our head but Ineos can end this dispute tomorrow if they step back from the brink and begin to work with their employees again instead of against them."
Unite accused Ineos of using the dispute to try to force through changes to pay, pensions and terms and conditions.
A strike at Grangemouth in 2008 is estimated to have cost the economy hundreds of millions of pounds.