Cardiff is "on the verge" of entering the Welsh Government's Covid-19 'red zone' according to Cardiff Council leader Huw Thomas.
Mr Thomas said there was a "real possibility" that Cardiff could enter the 'red zone' if cases continued to rise and warned that it would lead to further restrictions to contain the spread of the virus.
Speaking at a Cardiff Council meeting, Mr Thomas said "if case numbers continue to rise, there is a very real possibility that Cardiff will enter into the Welsh Government’s ‘red zone.’"
He continued: "If that were to happen then I fully expect that we will be implementing further restrictions – as seen elsewhere in the city region - and potentially at speed, in order to contain and suppress the virus."
He also announced a series of extra measures that are going to be introduced in Cardiff and the Vale of Glamorgan to slow down transmission.
These include limiting indoor visits to care homes and increasing council work with universities to "strengthen messages" on students complying with the regulations.
On Thursday, Cardiff Council leader Huw Thomas said the capital was "yet" to face local lockdown measures but had seen 38.2 cases of Covid-19 per 100,000 people over the past five days.
Over the past seven days, Cardiff reached a test positivity rate of 3.8%, exceeding the Welsh Government's "amber" threshold of 2.5% - part of its "traffic light roadmap" strategy for managing the pandemic.
A local lockdown in Caerphilly county borough will continue for "at least a further seven days", the Welsh Government has confirmed.
Health Minister Vaughan Gething said a review of the restrictions, which were enforced on September 8, had been carried out.
Mr Gething said cases of coronavirus had "declined steadily" since the local lockdown but there was still "some way to go" and infection rates remained high.
"After discussing the situation with the local authority, we have decided to leave the restrictions in place for at least a further seven days," Mr Gething said.
"If we continue to see a further reduction in cases in the borough, we hope we will be able to consider relaxing the local restrictions."
The warning comes after it was announced that pub-goers in Wales will be given an extra 20 minutes to finish their drinks after last orders, with the country's new 10pm cut-off for alcohol sales now in force.
From 6pm on Thursday, changes to coronavirus regulations mean Welsh hospitality businesses including pubs, cafes, restaurants, sports clubs and casinos must not supply alcohol between 10pm and 6am the following day.
Licensed premises will only be able to provide table service for customers when consuming food or drink, and following a 20-minute period to allow customers to finish their drinks at 10pm, must close by 10.20pm.