Health officials are expecting Nottingham to be placed in lockdown after a surge in Covid-19 cases.
The city's infection rate has soared, with 1,273 new cases recorded in the seven days to October 2 – the equivalent of 382.4 cases per 100,000 people.
This is up from 59.5 per 100,000 in the seven days to September 25.
The director of public health for Nottingham, Alison Challenger, said current restrictions in the city "are no longer enough to stop the spread of the virus".
The rising rate has coincided with a recent outbreak at the University of Nottingham, as figures on its website showed 425 students had tested positive for Covid-19 during the week ending last Friday.
The numbers included 226 students in private accommodation and 106 in halls of residence.
Eight members of staff were also classed as "active confirmed cases" over the same time.
A spokeswoman for the university, which has around 35,000 students, said: "Alongside the national Pillar 2 testing regime for people with symptoms of Covid-19, the university has also commenced its own asymptomatic testing programme which will identify cases earlier and more quickly.
"While this will mean that our case data will be higher than other universities, we can identify cases that otherwise would remain undetected and thereby reduce asymptomatic transmission and the number of future cases."
Nottingham City Council said it was expecting the Government to introduce tougher rules later this week, "similar to those introduced in other cities such as Liverpool, Manchester and Leeds".
People in Nottingham are urged to follower stricter guidelines to help stop the spread of Covid-19, following a dramatic increase in positive cases in the cityhttps://t.co/4WYGWefPMrpic.twitter.com/ijFWNrdDKr
— 🌈My Nottingham (@MyNottingham) October 6, 2020
The council has asked people in the city to "take urgent steps" and to "not mix indoors with people from other households".
Ms Challenger said: "We are seeing a dramatic increase in Covid-19 cases in Nottingham. Our rate of infection is now rising higher than many other parts of the country.
"This is a significant and worrying change. It means the measures we currently have in place are no longer enough to stop the spread of the virus in our city. We will have to do more to keep people safe in Nottingham.
"We would urge people to take action now and not mix indoors with people from other households. It remains OK to mix with those in your support bubbles unless someone has tested positive or has symptoms.
"We would ask people who have symptoms of Covid-19 – high temperature, continuous cough or loss of taste or smell – to self-isolate immediately and book a test by calling 119.
"And we strongly advise young people, including students in the city, to remain in their social bubbles and not mix in their homes with people from other households."
Council leader David Mellen said: "It is important to acknowledge that the majority of people are following the correct behaviours and playing their part in keeping our city safe, and we thank them for this.
"However, it is clear from the rate of infection that we must take more precautions. Nobody can afford to be complacent.
"Everyone needs to ask themselves, 'am I doing enough to guard against a disease that could harm me, or the person next to me or my loved ones?'
"If not, you need to change your approach and stick rigidly to the rules, if we are to see a reduction in the number of cases that are currently sweeping through our city.
"This will not be easy for any of us. We have been living with Covid-19 in our city and our communities for over eight months. Our lives have been restricted, we feel inconvenienced, and we all have worry and anxiety over our health and wellbeing. Some of us, sadly, may have lost loved ones to the virus.
"We are reaching a critical point in managing the spread of the virus as we head towards winter. So we have to keep going.
"We have to continue to work together by sticking to the rules and following a few important rules and guidelines. This will help to stop the spread of Covid-19 in Nottingham."