The future of hundreds of call centre workers is uncertain after supermarket giant Sainsbury's ended its contract with Teleperformance.
The call centre operator employs more than 2,000 people in Northern Ireland.
Its contract with Sainsbury's will terminate in mid-September.
The supermarket chain said it had been given "assurances that all colleagues affected by this change will be offered new roles."
But in a letter seen by the BBC, Teleperformance suggested there may be some redundancies.
In a letter, employees were told that it is "not a reflection of you or your work - it is a reflection of a very challenging market that is mature and therefore highly competitive".
With call centres in Bangor, Newry and Enniskillen, Teleperformance has provided customer service for Sainsbury's for 17 years.
Sainsbury's told the BBC that about 200 people work for the supermarket chain at the Bangor call centre, with a further 150 in Newry.
A Sainsbury's spokesperson said Teleperformance has given "assurances that all colleagues affected by this change will be offered new roles".
"We regularly review our business to ensure we're operating as efficiently and effectively as possible, so that we can provide our customers with the best possible service," they added.
"Following a recent review, we are making changes to our out-sourced customer contact centres."
But in a letter seen by the BBC, Teleperformance said it is still waiting for details of a new supplier to transfer employee contracts.
It added that it is the company's "preference to retain everyone who currently works on the Sainsbury's account".
A spokesperson for Teleperformance said: "Based on a client strategy change, we recently announced to our employees a realignment of jobs.
"This will involve redeployment to other accounts in our existing locations, or potential employment transfer to another company.
"We anticipate that this process will involve few, if any, redundancies given the employment opportunities we know to exist.
"We have had a relationship with Sainsbury's for more than 17 years and we can be very proud of the support that we have given to them and the service that we have provided to their customers."
The company said it will continue to provide services to Sainsbury's until December.
Consultations will be held before the contract is terminated.