Policing enforcement measures introduced by Boris Johnson in response to the Covid-19 pandemic will be a "real challenge" for officers, a police federation has warned.
Ken Marsh, chairman of the Metropolitan Police Federation, which represents officers in London, pleaded with the public to adhere to the measures as he warned that harsher ones could be introduced.
It comes after the Prime Minister placed the nation on lockdown, threatening police fines for anyone who ignores the new measures.
Mr Marsh said enforcement will be difficult amid "large amounts of sickness" among officers in the capital.
"So it will be very, very challenging and very, very difficult for us with what's put in front of us," he told Sky News.
"But we don't actually know what is being put in front of us yet and we're going to be asked to disperse crowds, it's going to be a real, real challenge.
"We will be dealing with it, but I'm not sure we will have the resources to be able to see it through."
He said the Army could step in and support police if numbers fall due to illness or self-isolation.
Police will have powers to disperse gatherings after Mr Johnson announced a ban on meetings of more than two people aside from those who live together.
Asked if major crime is no longer a priority, Mr Marsh said that although officers will police the same way "up to a certain degree", the coronavirus crisis had "taken over everything".
"This is the biggest thing that's ever happened in my lifetime and anyone's lifetime, really, and we need to get on top of it," he told Sky News.
"It's not to say we won't be policing, so people can't behave in any way they want, because we will still be policing in exactly the same way, but you will see measures changing as this changes."
Asked if he would like the measures go further, Mr Marsh said it could "absolutely become more draconian towards the public" if advice is ignored.
"Hopefully from this day, well, if they don't listen then there will be tougher measures," he said.
"I don't doubt for one minute, because the only thing you are going to see is hundreds and hundreds of people dying.
"And we don't want that, the police don't want that, I'm sure the public don't want that. It could be their loved ones. So we've got to work together."
- Police Federation (@PFEW_HQ) March 23, 2020
John Apter, national chairman of the Police Federation of England and Wales, said in a statement that "saving lives and protecting the public" is the number one priority.
"The practicalities of policing this lockdown will be challenging, but policing will do all it can to keep the public safe, but we need the public to support us," he said.
"I ask that the public heed the advice and stay at home unless absolutely necessary.
"This will allow police officers to concentrate on keeping the streets safe and deal with all the regular calls we receive.
"This is about saving lives and supporting our NHS. I ask that the public gives us their support in this time of crisis."