Fines have been issued to people attending a gym, a hotel and a house party as police enforce new coronavirus regulations.
Essex Police said 18 "reckless revellers" were fined almost £15,000 after officers interrupted a house party on Saturday, while in Merseyside, police found about 200 people partying in a hotel in the early hours of Sunday morning and broke up a gathering of 20 people in a gym on Saturday night.
A spokesman for Essex Police said officers attended a house in Bury Road, Sewardstonebury, at about 5pm on Saturday after reports of a party and when they arrived were initially refused entry by people inside who claimed to be making a music video.
Eighteen people inside the property, 17 from London and one from Essex, were fined £800 each following the introduction of higher penalties, the force said.
Deputy Chief Constable Pippa Mills said: "These selfish individuals not only have no regard for their own safety, but they clearly didn't give a second thought for the safety of the local community, the police officers who had to attend to deal with their reckless behaviour or the NHS who are under unbelievable pressure."
The force said an investigation is under way to establish whether two previous unlawful gatherings at the vacant, rented property were organised by the same person.
In Merseyside, police issued fixed penalty notices to 19 people who were found in Shred Fast Gym on Long Lane in Aintree at 10.30pm on Saturday.
The force, which has reported the business owner to the local authority, said those attending were not wearing PPE or social distancing and had travelled from areas including Billinge, Widnes, Wirral and Southport.
Assistant Chief Constable Rob Carden wrote on Twitter: "Twenty people on yoga mats burning pieces of paper with negative thoughts written on them have now been given new pieces of paper by @MerseyPolice with the words 'fixed penalty notice' printed on them.
"Seriously, if we don't back the 'lockdown' we are all in it for longer."
At 3.15am, officers found around 200 people at the Richmond Hotel in Liverpool city centre where four parties were going on, the force said.
A police spokesman said 13 fixed penalty notices were issued, 11 documented warnings were given and everyone who was not a legitimate guest at the hotel was removed.
One woman was arrested on suspicion of breaching coronavirus legislation and two counts of assaulting a constable and a man was arrested as he was wanted, the force said.
Chief Superintendent Matt Boyle said: "This sort of behaviour is unbelievable and unacceptable and officers should not be confronted with abuse and violence when attempting to uphold the law, which most people are rightly abiding by."
In London, 72 people were reported for the consideration of fixed penalty notices of £800 when officers were called to a party on a moored boat in North Acton, Ealing, shortly after 11pm on Saturday, the Metropolitan Police said.
A force spokesman said the organiser of the event, which appeared to have been arranged on social media, was identified and reported for consideration of a £10,000 fixed penalty notice.
The latest coronavirus regulations in England, which came into force at 5pm on Friday, include fines of £800 for people caught at house parties with groups of more than 15 people and will double after each offence, up to a maximum of £6,400 for repeat offenders.