Households in Birmingham have been banned from mixing in new lockdown measures announced following a spike in coronavirus cases
The city now has the second highest rate of Covid-19 infection in England, behind Bolton.
The measures also cover neighbouring Sandwell and Solihull, affecting more than 1.6 million people in total.
The restrictions will begin on Tuesday, it was announced at a regional meeting of council leaders.
West Midlands mayor Andy Street said: "The areas will now be escalated to an area of national intervention, with a ban on people socialising with people outside their own household."
The restrictions were not about "prevention of schools, workplaces, transport" but about mixing of households, he said.
The rate of coronavirus infection in Birmingham on 7 September was 85.4 per 100,000 people, up from 32 in the previous week.
Mr Street said residents were being advised to avoid household mixing before Tuesday's rules come into effect as it had been identified "as one of the drivers of transmission".
A government announcement on further measures, potentially affecting other areas of the country, would be made later, Mr Street added.
Under the new rules, people are banned from meeting others who are not in their household or support bubble, indoors or in private gardens.