The city, which is under Tier 3 restrictions, has the third-highest number of hospital admissions for COVID-19 in Europe.

The mayor of Liverpool says pictures of people partying on the street have "shamed" the city.

Joe Anderson posted on Twitter: "These pictures shame our city, attacking our brave police officers is unacceptable.

"Our health service is creaking, 300 in hospital and 30 people dead in week. Ignoring these facts is why we are in Tier 3 measures."

It follows pictures of crowds ignoring social distancing and dancing in Concert Square last night, one of the city's busiest nightlife hotspots, ahead of the city entering Tier 3 restrictions today.

The "large crowd" had to be dispersed after pubs closed at 10pm last night - two hours before the tough new coronavirus restrictions were imposed at midnight.

A video posted to Snapchat that showed last night's crowds was captioned: "Herd immunity, here we come."

In another piece of footage, apparently filmed from a nearby flat, a police car could be seen driving through a crowd while revellers banged their hands on the side of the vehicle.

Few appeared to be wearing masks or following COVID-19 social distancing measures.

In a statement, Merseyside Police told Sky News that a large crowd was dispersed quickly and safely - and officers were stood down after all businesses in the area managed to close.

"While we understand how the new rules which are due to be implemented today are frustrating for some, we would continue to advise everyone to abide by them - including keeping social distancing - for the safety of everyone," Chief Superintendent Peter Costello said.

According to the Liverpool Echo, a police car was attacked in Concert Square - with a witness claiming, "a large group of young partygoers were defying every social distancing rule imaginable".

City centre councillor Nick Small wrote on Twitter: "Idiots putting themselves, their friends, families and everyone else at risk, destroying jobs and our hospitality sector while they do it."

From Wednesday, Liverpool and the neighbouring five boroughs which make up the city region will be under Tier 3 coronavirus measures, which include the closure of bars, pubs which do not serve meals, gyms, betting shops and casinos.

Residents are also banned from socialising with other households indoors and outdoors, including in private gardens.

Liverpool recorded 3,164 new COVID-19 cases in the seven days to 10 October - the equivalent of 635.3 cases per 100,000 people. This is compared with 555 in the seven days to 3 October.

It has the third-highest number of hospital admissions for COVID-19 patients in Europe, and more than 95% of the city's intensive care beds are currently occupied.

Intensive care doctors working in the city told Sky's Inzamam Rashid that they are "disgusted" by what happened, with one saying: "They don't care that people are dying from this disease, it is heart-breaking to watch."

Another doctor told Sky News: "We have limited capacity in our [intensive treatment units] across the network, but more worryingly, we have people in the corridors on trolleys waiting for beds.

"We are running at 100% capacity. Our Emergency Departments are overcrowded. No social distancing possible.

"I am dreading we are heading towards a disaster. Then you see crowds behaving such a way. I am really devastated and disgusted."

Work and Pensions Secretary Therese Coffey told Kay Burley that the scenes were "irresponsible and really disappointing".

"It's gatherings like that which unfortunately don't help in any way to bring down the escalation of the virus."

Currently, the Liverpool City Region is the only area to fall into the "very high" alert level - but Sky News understands that a "gold command" meeting is going to be held to decide whether nearby Greater Manchester and Lancashire should also fall into this category.

On Monday, England's chief medical officer Chris Witty said Tier 3 restrictions "will not be sufficient" to slow COVID-19 infections alone.

Speaking at a Downing Street news briefing shortly after Boris Johnson confirmed the new tiered system Professor Whitty said: "I am not confident - and nor is anybody confident - that the Tier 3 proposals for the highest rates, if we did the absolute base case and nothing more, would be enough to get on top of it."

Meanwhile, the prime minister has been told a "circuit-breaker" lockdown could save thousands of lives by the end of the year.

A paper by members of the Scientific Advisory Group for Emergencies (Sage) reportedly calculates that more than 7,000 lives could be saved if schools are closed and people are ordered to stay at home from October 24 for two weeks.

Eyewitness: People seem resigned to more restrictions on their daily lives
By Alex Rossi, news correspondent

It was Liverpool's last night out before the lockdown - and most streets were deserted.

In the Dead Crafty Beer Company - a 15-minute walk from Concert Square - they called last orders at 9.15pm. As the bell sounded, customers seemed resigned to more restrictions on their daily lives.

The owner, Gareth Morgan, told me he will sell beer online to keep going, but he's under no illusions it will be a tough few months - and he is frustrated at what the government is doing.

He told Sky News: "It feels like we're just being kicked to the kerb. There's no evidence backing up that hospitality is causing this massive spike that's happened in Liverpool. I don't deny the spike.

"There's a massive influx of students, we're a massive university town, all the offices have gone back to work, the schools have gone back - and hospitality, that's been trading for two-and-a-half months without a large spike, is now being blamed."

The rules coming into force will not only affect the hospitality sector. Gyms, betting shops and casinos will also close - and people will be restricted from socialising outside their household in any indoor or outdoor setting.

The government says the restrictions in Liverpool are necessary to bring down the R number - the infection rate.

Deaths in Liverpool have doubled in the past week, and hospital admissions are going up all the time.

The virus is surging - and worryingly, public health officials say the virus is still in the growth phase.

But Westminster is a long way from here - and many people are angry with how the rules have been handed down.

Independent gym owners also say the closures are not evidence based - and shutting them down will damage people's mental and physical wellbeing, as well as causing viable businesses to go under.

Nick Whitcombe, from Body Tech Fitness, said he will defy the new restrictions and keep his doors open.

He added: "How we look at this is you have the value of the fine versus the cost of losing the entire business. This is fight or flight, we have no option here.

"This isn't a case of if we close, we lose a little bit of money. If we close with the financial package that's on the table, we will go out of business. This is our only option. We have no choice - it's either pay the fine or lose absolutely everything."

The measures may be reviewed in four weeks' time, but the future here is far from certain.

And the question is will other areas soon be joining this city in the harshest lockdown category in the next few days.