Health Secretary Matt Hancock has warned Britain is at a "tipping point" as he refused to rule out a second national coronavirus lockdown if the public fails to follow social distancing rules.
"The nation faces a tipping point," he told Sunday programme.
"We have a choice. Either everybody follows the rules - the rule of six and the need to self-isolate if you have a positive test or if you are contacted by NHS Test and Trace - or we will have to take more measures.
"I don't want to see more measures, more restrictive measures, but if people don't follow the rules that is how the virus spreads."
The Health Secretary said meetings would be happening today to discuss new coronavirus restrictions in London.
"I've had discussions this week with the Mayor of London and the teams are meeting today to discuss further what might be needed," he told Sky News.
His comments came as the Government announced people in England will face fines of up to $19,100 (£10,000 ) if they refuse an order to self-isolate.
Hancock said: "We will support people who do the right thing and we will come down hard on people who do the wrong thing."
Meanwhile, trials of the Oxford vaccine have been paused twice after two participants, both British women, sequentially developed transverse myelitis, an inflammation of the spinal cord that can cause paralysis.
The first pause, in July, was not publicly revealed and the trial was restarted after it was determined the volunteer had multiple sclerosis, a condition that can cause the same neurological reaction.
The second pause, widely reported two weeks ago, followed the second suspected case of the condition in a volunteer who is said to have been hospitalised but now recovered.
Trials of the vaccine have since been restarted in Britain, Brazil, India and South Africa, but are still on pause in the United States where the legal and historical context means regulators tend to take a tougher stance.
On Saturday, AstraZenica released further data on its trial protocols, but US experts continued to raise concerns.
There were 3899 new reported cases of Covid-19 in Britain on Sunday (UK time), compared with 4422 the day before, the Government reported on its website.
Overall, the number of cases had risen sharply in recent weeks, prompting tighter restrictions across the country and several local lockdowns.