Hundreds of Oxfam workers are to launch a wave of strikes from Friday for the first time in the charity’s history in a dispute over pay.
Members of Unite who work in Oxfam’s shops and offices, will walk out for 17 days throughout December.
The union says average wages have been cut by 21% in real terms since 2018.
The workers voted by 83% in favour of strike action in a ballot with an 82% turnout after they rejected a pay offer of £1,750 or 6%, whichever is higher, plus a one-off payment of £1,000 for the lowest earners, said Unite.
Unite general secretary Sharon Graham said: “Oxfam wants to end poverty and says it is on the side of unions.
"Yet its own workers report having to use food banks, it refuses to engage with the only union representing its workforce and it is considering using unpaid labour to break a strike.
"This is rank hypocrisy from an organisation that should know better."
Ms Graham added: “Oxfam is an extremely wealthy organisation and can afford to put forward an acceptable offer without impacting its charity work in the slightest.
"Its workers have their union’s total and unflinching support as they strike to make sure that happens.”
The workers will strike at Oxfam offices and more than 200 shops on December 8-9, 14-17, 20-24 and 26-31 – and Unite warned industrial action will intensify if the dispute is not resolved.
An Oxfam spokesperson said: “While we are disappointed that tomorrow’s strike is going ahead, we do understand the frustration of colleagues who are facing a steeply rising cost of living.
“Communities we work with to fight poverty are also facing rising costs, so our resources are stretched but we are committed to finding a solution.
"We hope that discussions with Unite taking place at Acas tomorrow will help us move forward.
“We are doing everything we can to minimise disruption and to support all colleagues – those on strike and those who are working – through this period.”
Want a quick and expert briefing on the biggest news stories? Listen to our latest podcasts to find out What You Need To Know...