A major UK supermarket has offered bonuses to its frontline staff - but not those taken on to help during the coronavirus pandemic.
The union GMB described Tesco's decision as "a disgrace" and called on the company to rethink only paying the sum to permanent staff.
A worker, who wished to remain anonymous, said he felt undervalued.
Tesco said it was "very grateful" to its temporary workers and they played a "crucial role" in its business.
The store is paying a 10% bonus on the usual hourly rate between 6 March and 30 May "for going above and beyond" and "in recognition of their incredible effort, and recognising the challenges that lie ahead".
However temporary members of staff taken on to deal with the pandemic will miss out.
GMB Senior Organiser Mike Payne said: "For an employer to single out a group of workers in this way, during the pandemic, is nothing short of a disgrace.
"Workers are risking their health and the health of their families in answering the call to assist in this pandemic.
"Tesco need to move quickly to rectify the situation."
Wales TUC General Secretary Shavanah Taj said the union was "encouraged" to see employers recognise the hard work of staff but they "must ensure every worker is fairly rewarded for their efforts during this difficult time".
A man taken on to work in a south Wales store to deal with increased demand during the pandemic said he was among those missing out.
"We have done the same if not more work than most of the full-time staff," he said.
"We are working night shifts mostly, for £8.72 per hour plus an extra pound or so per hour for the night shift.
"It may not seem like a lot of money to some having an extra 10% on top of what you have earned, but I look on it as a thank you for your hard work, commitment and time.
"We are not being treated as equal... I don't see why we should be treated any different."
He added the job was taking its toll on some colleagues.
"I have seen quite a few of the people taken on having quit the job because it is so demanding and such hard work."
A Tesco spokeswoman said: "Our temporary colleagues continue to play a crucial role in our business, ensuring customers can get the food and essentials they need in store and through our home delivery service.
"We are very grateful to them, and to all our colleagues, for their continued contribution during this unprecedented time."
What are other supermarkets doing?
Sainsbury's said it was paying an extra 10% to permanent - and temporary - colleagues between 8 March and 5 April as a "small thank you for all their efforts", describing staff's commitment as "extraordinary".
Co-op's bonus of an extra week's pay will be awarded to anyone, temporary or permanent, who was in employment on 13 March when the scheme was initiated.
At Asda, everyone is eligible for an extra week's pay as long as they have served their 12-week probationary period by the time the bonus is paid in June.
Marks and Spencer said rather than making temporary hires it had transferred colleagues from other departments to support food, but all would be eligible for the 15% bonus.
Morrisons said its frontline supermarket staff would receive a threefold increase in bonus from last year, which would be 6% of the entire year's pay for the next 12 months rather than a few weeks. The store said both permanent and temporary colleagues will be eligible.
All Aldi store and distribution staff will receive a 10% bonus on hours worked between 9 March and the end of April, and Lidl workers across the business are being given a £150 voucher.
Waitrose is paying its non-managerial and first-level management partners £25 for each week worked in May and June.