Figures have revealed cases of Covid-19 are continuing to rise in Rhondda Cynon Taf, after the county was placed under stricter measures.
A further 56 cases have been confirmed there in the last 24 hours, with nearly eight per cent of people who were tested showing a positive result.
The area, which has a population of around 240,000 people, has been under local lockdown since 6pm on 17 September.
The total number of people who have died with Covid-19 in Wales remains at 1,603, with no new deaths reported.
The figures come after England's health secretary said there was a danger cases could “shoot through the roof” unless effective action was taken to halt the spread of the virus.
Of the 199 cases confirmed in Wales in the past 24 hours, 80 were in the Cwm Taf Morgannwg Health Board area - which covers Rhondda Cynon Taf, Merthyr Tydfil and Bridgend.
The health board has temporarily restricted hospital visits in a bid to stop the spread of the virus.
A council leader there said he is becoming "increasingly concerned" by the figures.
Leader of Rhondda Cynon Taf Council, Andrew Morgan, said: "If we are to see the Welsh Government intervention measures reduced and then removed, we have to get on top of this and that means every resident has to play their part.
"Follow the basics in terms of good hand hygiene, wear a mask where needed and remember to social distance, and also take note of the new restrictions on households and travel."
He added that the health board area has seen a rise in the number of older people catching the virus, and an increasing number of hospital admissions.
"I would appeal to everyone to understand the seriousness of the current situation and act now before we face further local restrictions."
What do the numbers say?
In Bridgend, 6.8 per cent of people who were tested in the last 24 hours showed a positive result. There have been 21 new cases confirmed there.
The county is being closely monitored, with the public being warned to follow guidelines or risk being placed under tighter restrictions.
The Public Health Wales figures showed a drop in confirmed cases in Merthyr Tydfil between Saturday and Sunday - going from 27 to just three.
Carmarthenshire saw a rise from ten new cases to 19 over a 24-hour period, with 6.5 per cent of people tested being positive.
There were also 17 new cases in Cardiff, but less than three per cent of people tested there were positive.
Ceredigion and Pembrokeshire were the only two counties with no confirmed cases, with just three confirmed cases across the two regions in the past seven days.
Public Health Wales said a lag in receiving data means the overall figures are likely to be an underestimate.
How many people have tested positive in my area?
The following figures show the percentage of positive tests in each area, as of 20 September:
Blaenau Gwent: 4.6%
Vale of Glamorgan: 3.1%
Merthyr Tydfil: 1.3%
Rhondda Cynon Taf: 7.9%
Neath Port Talbot: 1.2%