Strict new restrictions have been unveiled for Birmingham, Solihull and Sandwell following a surge in coronavirus cases.
From Tuesday, people in these areas will no longer be allowed to mix with those from other households.
The new rules come amid a spike in Covid-19 infections in each of the areas.
West Midlands mayor Andy Street said: “The following areas will now be escalated to an area of national intervention, with a ban on people socialising with people outside their own household.
“The ban will take effect from Tuesday 15th September, but residents are advised to avoid household mixing before then as it has been identified as one of the drivers of transmission.”
He added that the bans applied to the whole of Birmingham, Sandwell and Solihull.
NHS data reveals there were 892 new Covid-19 cases in Birmingham in the week up to September 8 – one of the highest figures seen in the city since the peak in April.
During the same period, there was an infection rate of 78.2 cases per 100,000 people.
The government usually introduces quarantine restrictions for foreign countries when the rate reaches 20 per 100,000.
The current positive infections tally puts Birmingham third in a national table of local authority areas of highest infection rates, behind Bolton and Sunderland.
Birmingham’s director of public health Dr Justin Varney said the uptick in Covid-19 infections was “linked primarily to private household gatherings”, at the end of August and across the bank holiday weekend.
An increase in testing had also turned up more positive results, he added.
A whistleblowers’ hotline set up in August allowing people to report rule-breaking businesses has had more than 800 calls.
