Up to 1,100 jobs are being axed at supermarket giant Tesco as the group confirmed plans to shut its call centre in Cardiff.
Tesco said it was set to close the 11-year-old site in February next year and move the customer services operations to its remaining call centre in Dundee.
The group said 1,100 staff in Cardiff would be affected, although it plans to create 250 jobs at its Dundee office as part of the move.
Matt Davies, UK chief executive of Tesco, said: "The retail sector is facing unprecedented challenges and we must ensure we run our business in a sustainable and cost-effective way, while meeting the changing needs of our customers.
"To help us achieve this, we've taken the difficult decision to close our customer service operations in Cardiff.
"We realise this will have a significant effect on colleagues in the Cardiff area, and our priority now is to continue to do all we can to support them at this time."
Trade union Usdaw said the decision was "devastating" for affected employees.
Nick Ireland, d ivisional officer of Usdaw, said: "Tesco's Cardiff call centre staff are understandably shocked by th e announcement of the company's planned closure.
"This is clearly devastating news for our members and will have a wider impact on South Wales, as so many jobs are potentially lost to our local economy."
Tesco said it would be offering to move some of the affected staff to the Dundee site , where it already has 900 workers.
It will now enter consultation talks with trade unions.
Details of the call centre plans come in a difficult week for Tesco after its home delivery service was hit by a computer glitch on Tuesday, which saw thousands of orders cancelled or postponed.
Up to 10% of all orders were affected nationwide, leaving affected customers furious.
Ken Skates, Welsh Government Economic Secretary, said: "This is devastating news, especially for the workers and their families facing redundancies at Tesco House.
"We will work in close collaboration with Tesco and the major support agencies locally, including Careers Wales, Jobcentre Plus, colleges and the local authority to deliver the best possible support for the workers facing an uncertain future."
Councillor Huw Thomas, leader of Cardiff Council, said the council would be seeking an urgent meeting with the Tesco chief executive.
"Tesco is a strategic company in Wales and, given the current economic climate in Cardiff, this decision is both surprising and disappointing," he said.
"We need to understand the reasons why this decision has been taken and the redundancy package that is being offered to those affected.
"Cardiff has recently been announced as the third-best office location in the UK and, with levels of investment rising, our city is an increasingly attractive place to do business.
"We will do everything within our powers and remit to find the best possible solution for those affected by this decision."
Secretary of State for Wales Alun Cairns said: "While I understand that this is a commercial decision for Tesco, the news that there will be a significant number of job losses at its Cardiff site will cause a great deal of concern to the workers, families and communities affected.
"I am receiving regular updates from the company and am committed to working with relevant agencies, local authorities and the Welsh Government to offer all the support we can.
"Our priorities as a Government are to continue to focus on creating the right conditions for economic growth by exporting goods and services and attracting inward investment.
"Today's news is another reminder of the importance of retaining jobs, promote business opportunities in Wales and to ensure our country remains a competitive place to do business."