Four more counties in south Wales will go into lockdown from 18:00 BST on Tuesday, meaning more than a quarter of the Welsh population will be under tighter restrictions.
Merthyr Tydfil, Bridgend, Blaenau Gwent and Newport will have the same restrictions as Rhondda Cynon Taf.
People will not be able to enter or leave those areas except for a limited number of exemptions, such as work.
Licensed premises like pubs will need to shut by 23:00 every night.
People will only be able to meet others not in their own household outdoors - meetings with people from their extended households indoors will be banned in the four areas.
The pub rule will also be extended to Caerphilly county borough, which was put under local restrictions last week.
The new measures affect 431,000 people and means more than 850,000 people in Wales are under local lockdown, with restrictions brought in to Caerphilly county borough and Rhondda Cynon Taf earlier in September.
Health Minister Vaughan Gething said Mondayâ€™s extension followed rises in Covid-19 cases in the four counties.
At a press conference Mr Gething said he would hold “an urgent meeting” on Tuesday with all councils, health boards and police forces in south Wales.
It will discuss the wider regional situation and whether further measures are needed.
Earlier, senior UK government advisers warned of a “six-month problem” of rising cases and potentially 50,000 new deaths.
Mr Gething said he could not “definitively” give a timescale of how long lockdown measures would be needed.
He said “all-Wales” measure may be needed to tackle the virus.
But Mr Gething said such action may be short of the full lockdown imposed on 23 March.
What does local lockdown mean?
If you live in one of the six counties affected, the rules mean you cannot visit or leave the areas affected without a “reasonable excuse”.
That can include:
- For work, if you cannot work from home
- For education
- For buying essentials like food or medicine
- To provide or receive emergency assistance
- To meet a legal obligation, and to access or receive public services
- To avoid injury or illness or escape a risk of harm
Motorists can continue to use the M4 and other major roads - you can drive in and out of the areas as long as you do not stop.
A call between Prime Minister Boris Johnson and Walesâ€™ First Minister Mark Drakeford is expected to take place on Monday afternoon.
Mr Gething said it may be the case that UK-wide measures would be taken, adding the call would be a “helpful step forward”.
The health minister said the incidence rate in Merthyr Tydfil was high, but cases appeared to be mainly focused around two distinct clusters, linked to a large employer and a pub.
What is happening in the four areas?
BridgendÂ was a “growing concern”, the minister said, because there had been a sharp rise in cases in a short space of time.
“We have identified a small number of clusters in Bridgend borough, but we are worried the pattern is similar to what we have seen in Rhondda Cynon Taf”.
Newport is seeing “a wide spread of cases across the city, which are not linked to a particular cluster or showing links with existing cases”.
In Blaenau Gwent, Mr Gething said there had been cases linked to pubs and a lack of social distancing but there have also been cases in care home staff and in secondary schools in the area.