Last week’s strikes by Oxfam workers were part of 17 planned days of walkouts over Christmas.
However, Unite has warned that if its members vote against the deal, strike action will resume on 20 December and last up to and including 31 December.
On Friday, 500 workers at Oxfam offices and 200 charity shops began industrial action after rejecting a pay offer of £1,750 or a 6% rise, as well as a one-off payment of £1,000 for the lowest earners.
In November, Unite accused the anti-poverty charity of “hypocrisy”.
Oxfam, which opened its first charity shop in 1947, describes itself as a “global community of people who believe in a kinder, and radically better world, where everyone has the power to thrive not just survive”.
It says: “We believe we can overcome poverty by fighting the injustices and inequalities that fuel it.”
But last month Unite claimed that pay at the charity had fallen by 21% since 2018, when taking inflation into account.
It said: “Its own workforce is struggling to survive on poverty wages.”