The fines, which apply to people attending parties of more than 15 people, will increase with each offence to a maximum of £6,400.
Patel told a Downing Street press conference: “The science is clear. Such irresponsible behaviour poses a significant threat to public health.
“Not only to those in attendance but to our wonderful police officers who attend these events to shut them down.”
The £800 minimum fine is an increase on the previous £200 penalty for a first breach of Covid rules in England.
Martin Hewitt, chair of the National Police Chiefs’ Council, said officers have issued 250 fixed penalty notices to organisers of large gatherings since August.
He gave examples of lockdown-breaching house parties across the country, including one in Brick Lane, east London, last week – where more than 40 people attended and were “hostile to the police”, injuring three officers.
A party in Hertfordshire with more than 150 people was stopped by the police and several people fined.
“They had music equipment, mixing decks, amplifiers, all being used by the organisers,” Hewitt said.
Breaking the rules in the way it’s been described today is like switching on a light in the middle of a blackout in the BlitzNHS England medical director for London, Vin Diwakar
Meanwhile, an officer who policed an anti-lockdown protest in Bournemouth has since been hospitalised with Covid.
Hewitt said large gatherings such as house parties are “dangerous, irresponsible, and totally unacceptable”.
He told the briefing: “I hope that the likelihood of an increased fine acts as a disincentive for those people who are thinking of attending or organising such events.”
He said officers will not “waste time” trying to reason with people breaking the rules in such a way.
He said: “When we see people that are putting themselves and others in danger, we will not waste time trying to reason with them.
“They are demonstrating no regard for the safety of others, or even for themselves.”
NHS England regional medical director for London, Dr Vin Diwakar compared breaking the rules to turning on a light in the middle of a blackout during the Blitz.
“This is the biggest health emergency to face this country since the Second World War,” he told the press conference.
“For me and my colleagues in the NHS, breaking the rules in the way it’s been described today is like switching on a light in the middle of a blackout in the Blitz.
“It doesn’t just put you at risk in your house, it puts your whole street and the whole of your community at risk and that is why it is absolutely critical that for now, based on the information that we have got, please follow the rules, please stay at home, please help to save lives.”
Patel echoed his comments, saying breaches of lockdown rules were “costing lives”.
Speaking to a Downing Street press conference, she said: “We are clear that the majority of the British public are following the rules.
“You’ve heard today, quite frankly, some pretty shocking examples [of rule breaches] from Martin [Hewitt] – I hear examples like that every single day from police and it is really just very disturbing to hear examples of the egregious breaches.
“The majority of the British public who are complying with the rules will want that assurance, they want to know that when it comes to policing that those who are breaking the rules are being fined.
“These egregious breaches are costing lives.”