Different households in Leeds will be banned from meeting in private homes or gardens in a bid to slow rising Covid-19 rates, the government has confirmed.
The measure will begin at midnight and would bring the city in line with rules in Bradford, Kirklees and Calderdale, said council leader Judith Blake.
Health Secretary Matt Hancock confirmed the rule in a written statement.
The city council said there had been a "steep rise" in infections, with the rate at 98.5 per 100,000 people.
The move will have an impact on 780,000 people but some exemptions are expected, including for those with caring responsibilities.
'Safety comes first'
Residents in Bradford, Kirklees and Calderdale are currently strongly advised not to socialise in any public venues with people they do not live with.
The council said the measures for Leeds will match those areas, with the national "rule of six'" and 22:00 venue curfew continuing alongside.
Councillors asked the government to allow households to meet in private gardens, but this request was rejected.
In his statement, Mr Hancock said: "We are making regulations which take effect from Saturday, 26 September and will impose restrictions on inter-household mixing in private dwellings and gardens in Leeds, Stockport, Wigan and Blackpool.
"People who live in these areas will not be allowed to gather in a private dwelling or garden with any other household unless in a support bubble.
"People from anywhere else will also not be allowed to gather with another household in a private dwelling or garden in these areas."
Ms Blake said the duration of the new measures "will depend on everyone playing their part".
"We are acutely aware that nobody wants to see further restrictions placed on life in Leeds and alongside our partners we have been doing absolutely everything within our power to avoid that," she said.
"But the safety of the city and the public simply has to come first and we have now reached a point where we all need to take additional steps to contain the spread of this terrible virus within our communities."
Victoria Eaton, the city's director of public health, said there was "very widespread community transmissions right across the city", with compliance with self-isolation rules still low.
"The expectation is the restrictions will be in place for a longer period of time, potentially right through the winter," she said.
Rules for Leeds
- Not to meet people you do not live with inside a private home or garden, except where you have formed a support bubble
- Not to visit someone else's home or garden even if they live outside of Leeds, unless they are in your support bubble
- You are advised not to socialise with people you do not live with in any public venue in Leeds or elsewhere
- Examples of these include pubs, restaurants, cafes, shops, places of worship, community centres, leisure or entertainment venues, visitor attractions and parks
- Friends and family can still provide informal childcare for children under 14
- You are advised not to visit friends or family in care homes, other than in exceptional circumstances
- Exemptions to the home and garden rule include visiting a person who is dying, to fulfil a legal obligation, for work purposes, for the provision of voluntary or charitable services, for the purposes of education or training, to provide emergency assistance, to facilitate a house move, to provide care or assistance to a vulnerable person and to attend a birth at the mother's request
Source: Leeds City Council
By David Rhodes, BBC Yorkshire data journalist
Despite repeated warnings from Leeds City Council, the number of Covid-19 cases in the city has risen throughout September.
In the seven days to 21 September there was a record 829 new infections identified. That surpasses the peak of new cases in the first wave of the pandemic back in late April.
Whilst mass testing has only been available since May, the sharp increase in cases in the past month has alarmed officials - as the number of new cases has quadrupled in the space of three weeks.
Leeds is not alone in West Yorkshire - Bradford, Calderdale and Kirklees have all seen record numbers of new cases in the latest week's data.
Bradford, Kirklees and Calderdale have been part of local restrictions since July along with areas of east Lancashire and Greater Manchester.
While most of the rest of England had seen lower rates of new coronavirus infections over the summer, these three parts of West Yorkshire were regularly in the top 20 of the 315 districts and boroughs,
Leeds had been on Public Health England's watchlist as an "area of enhanced support", meaning it received greater national assistance and extra testing capacity, but had so far escaped the tighter restrictions of its neighbours.
Leeds is one of 32 local authority areas where the rate in the week to 21 September was in excess of 100 cases per 100,000 people.
There were 829 new infections in the city that week, up from 607 the week before, according to data released on Thursday.
Tom Riordan, chief executive of Leeds City Council, said: "It looks like we are in the middle of the second wave, so we do support these household restrictions having to be brought in at this stage.
"That is something we really need the people of the city to get behind."
'Expect this to last'
By James Vincent, BBC Yorkshire political editor
Expect this to last for a while.
The council doesn't know whether these new restrictions will still be in place at Christmas - but it's clear Leeds needs to be braced for a long haul.
The "rule of six" and the curfew on pubs and restaurants will stay in place - now it's likely that hundreds of thousands of people are going to be apart from their families for the foreseeable future.
It will come into force at midnight and although it will be reviewed weekly, it may not change for some time.