A series of strikes by workers at consumer goods giant Unilever will start on 18 January, with picket lines mounted at several sites in a worsening row over pensions.
Thousands of members of three trade unions will take industrial action over the next 11 days in protest at plans to close the company's final salary pension scheme.
Unilever said it had been given time to prepare for the action, which it described as "disproportionate", but unions claimed the walkouts will hit production of leading brands including Persil, PG Tips, Marmite, Pot Noodle, Lynx, Flora and Wall's ice cream.
Factories across the country will be hit by the stoppages, including Port Sunlight on the Wirral, Warrington, Norwich, Leeds, Gloucester, Trafford Park in Manchester, Purfleet in Essex and Ewloe in north Wales.
Union officials said workers were "furious" at the plans to scrap the final salary scheme, which they said would lead to pension cuts of between 20% and 40%.
The company maintained that almost 90% of its affected employees will retain 80% or more of their pension.
Unite has released a film on its website, spelling out its side of the dispute. National officer Jennie Formby said: "The hard working workforce made Unilever into the global giant it is today but consumers will soon know the company better for its greedy pensions snatch than its products.
"This film will be a best seller - it will be viewed millions of times. We urge shoppers to watch it and support workers in their fight to protect the pensions promises made to them.
"Unilever need to clean up their act. Get back round the table before you ruin the business' reputation for good."
Allan Black, national officer of the GMB said: "Unilever can afford to sustain the current pension scheme unchanged due to the profitability of the company.
"The unions are able to put forward constructive alternative proposals on pensions, but these have never been considered by Unilever."
Unilever said in a statement: "The reality is that the union representatives had multiple opportunities to help shape the greatly improved final outcome of consultation we reached in October, but unfortunately they decided to walk away from talks.
"Making these changes was a tough but necessary choice which reflects the realities of rising life expectancy and increased market volatility. We believe the provision of final salary pensions is a broken model which is no longer appropriate for Unilever. It is our responsibility to protect the long-term sustainability and competitiveness of our business, and to do so is in the best interests of our people.
"The pension arrangements which we plan to implement in July this year are exceptionally competitive, and were significantly enhanced in a total of 13 different ways as a result of the feedback we received from our employees during the 100 day consultation process. We believe these significant changes underscore the value and legitimacy of the consultation process which was concluded in early October."
Amanda Sourry, chairman of Unilever UK said: "By continuing to offer all of our employees a career average pension plan on their earnings up to £48,000, around 80% of our people will be fully covered by a defined benefit scheme.
"In addition, almost 90% of our affected UK employees will retain 80% or more of the pension they would have previously expected.
"It is currently not clear how the dispute with the trade unions will be resolved, but we are continuing to urge our employees who have participated in industrial action (approximately 2,000 from a total of 7,000 UK employees) to give further objective consideration to the very competitive new arrangements which are unavailable at most other companies in the UK."
Strikes will continue until the weekend of January 28.