Hundreds of drivers and warehouse workers at Tesco distribution sites are to be balloted for strike action in a row over pay.
Unite said 700 of its members in Belfast and Doncaster will vote next week after rejecting a two-year offer of 0% this year and 1.5% in 2016.
National officer Adrian Jones said: "Our members have been working very hard to get Tesco to the position where the company can announce promising financial results and be confident that it has turned the corner of the challenges of recent years.
"We don't want favours from the company but we believe that the current offer is far below what it can afford and what our members deserve.
"Unite members don't want to disrupt anyone's Christmas shopping but without a proper pay increase thousands of workers will not be able to enjoy their own Christmas in the way they deserve.
"We urge Tesco to revise its pitiful pay offer and avoid potential industrial action in the run up to Christmas."