The number of workers testing positive for coronavirus at an Anglesey chicken factory has risen to 158.
All staff at the 2 Sisters meat processing plant in Llangefni are self-isolating after a number of workers were confirmed to have the virus on Thursday.
A Welsh Government minister has not ruled out local lockdown measures to contain the outbreak.
Public Health Wales (PHW) said the number of cases was expected to rise.
Dr Christopher Johnson from PHW said 400 staff had been tested since the outbreak was confirmed on Thursday.
“As of 15:00 BST on Sunday 21 June we have recorded an increase of 83 confirmed positive cases identified over the past 24 hours,” he said.
“Testing of employees continues, and it is likely that some additional cases will be identified in the coming days.
“The increase in cases is as we anticipated when a focused track and trace programme is implemented, and does not mean that the spread of infection is increasing.”
Travel restrictions in Wales are due to be lifted from 6 July, allowing people to “travel as far as they like for all purposes”, as long as covid cases continue to fall.
But speaking on BBC Wales Politics Show, the Economy Minister Ken Skates said it was essential to make sure the Anglesey outbreak was “kept as local as possible”.
Mr Skates did not rule out restrictions remaining in place in Anglesey, and said the council, PHW and Betsi Cadwaladr health board were “right to contain the fallout from the 2 Sisters plant” and “making sure that spike is kept as local as possible”,
He said: “That will help contain the virus, and that, in turn, help Anglesey open up its economy sooner, and that is something I think the island will welcome and I think the entire population of Wales will welcome.”
Anglesey council has already confirmed schools will not reopen as planned on 29 June following incidents at the plant.
Testing sites were set up at Llangefni and Holyhead, and at an existing facility in Bangor, following the outbreak.
All staff and contractors working at the processing plant, which has 560 workers, have been asked to self-isolate for 14 days, and are being contacted for testing.
2 Sisters is one of the largest food producers in the UK and processes about a third of all the poultry products eaten each day from its sites across Britain.
It has suspended production and closed the factory, which supplies local authorities, hospitals, restaurants and small businesses, following the outbreak.
2 Sisters had said “the health, safety and well-being of our colleagues is ultimately the thing that matters most at our business”.
It added: “We will not tolerate any unnecessary risks – however small – for our existing loyal workforce at the facility.”
PHW, who are responding to the outbreak, thanked the workforce and wider community for their “swift co-operation” with the test and trace process.
“This rapid response is providing vital information to help minimise the further spread of Covid-19 locally,” said Dr Johnson.
“We must remember that Covid-19 has not gone away.
“Incidents like this show the potential for pockets of asymptomatic undiagnosed infection in the community, highlighting the importance of the adherence to social distancing and hygiene measures.”
Dr Johnson said rapid test and trace facilities had “helped identify this situation” and said health teams would keep measures in place to “bring the outbreak to a rapid conclusion”.
He added: “It therefore remains essential that all members of the public, including employees of 2 Sisters Food Group and their close contacts, continue to recognise the vital role they have in preventing the spread of coronavirus, to help keep Wales safe.”
Responding to the increase in confirmed cases, Anglesey council leader Llinos Medi said the outbreak was “causing concern on Anglesey”.
She said the authority’s thoughts were “with 2 Sisters’ employees and their families at this uncertain time” and urged all workers to get tested and to make sure they self-isolated.
“This is imperative to stop the spread and further positive cases in our communities,” she said.”The county council is working with partners across the Island to ensure those who are self-isolating, who have no support networks, are helped during this challenging period.”
The council leader said the authority would be holding discussions with the Welsh Government on Monday to see “what local lockdown looks like”.
“How do we enforce local lockdown, and also how do we support those businesses that would not be able to operate during a local lockdown, as well,” she added.
Is food safe?
The Food Standards Agency said it was “very unlikely you can catch coronavirus from food” as the virus is a respiratory illness.
The agency’s Caroline Kitson said the virus was “not known to be transmitted by exposure to food or food packaging”.