Parts of Wales have overtaken Leicester for rates of Covid, analysis shows.
Official statistics show that Merthyr Tydfil has recorded 179 cases per 100,000, compared with 141 per 100,000 in Leicester.
Cases in the Welsh borough have soared in the last week, up from 10 cases per 100,000.
However, health chiefs in Wales have said there is no evidence that the infections - linked to an outbreak at a meat plant - have spread to the community.
As a result, there are currently no plans to extend lockdown measures in the Merthyr Tydfil.
Public Health Wales has said the surge in cases stems from increased testing, after a cluster of 130 cases at the Kepak meat plant. Most of the positive cases were uncovered on the same day, leaving health chiefs hopeful that the outbreak can be stamped out.
Health Minister Vaughan Gething said: "Merthyr is a very small local authority, so that one incident with that number of positive cases has driven up their population count per head.
"What they don't have in Merthyr is sustained community transmission in the way they do have in Leicester, with lots of different pockets and clusters that aren't related to one particular workforce and the community around it. So that's why we're in a position where we don't need to take those wider community measures.”
It was announced on Thursday that bars, pubs, cafes and restaurants can begin to re-open outdoors in Wales from July 13 if cases of Covid continue to fall across the country.
Research into the spread of Covid in Leicester has linked it to a number of different environments, including food and clothing factories, outlets, and supermarkets.
Health officials have said the virus is circulating in the community, meaning that the city's lockdown has been extended for two weeks, while restrictions elsewhere have been eased.
Schools and non-essential retail in Leicester have also been closed.
Merthyr now has the highest infection rates, and has seen the biggest weekly increase, analysis of official figures shows.
Others to see rises include Knowsley, Bolton, and then Hammersmith and Fulham have seen the largest rises in infection rates. But these areas still saw fewer than 25 infections per 100,000 people in the week to 28 June. The biggest falls are in Wrexham and Anglesey, in Wales, followed by Barnsley, Rochdale and Bradford.