People ignoring Government advice by leaving their homes to socialise are "selfish" and could be costing lives, Health Minister Matt Hancock has said.
He would not rule out a full lockdown just as Downing Street also said Boris Johnson would not hesitate to take further action if stricter measures were needed to enforce social distancing.
The prime minister will address the nation at 8.30pm on Monday, after the usual daily Downing Street press conference did not take place.
But Boris Johnson is still expected to address the nation in some format later on Monday, Number 10 sources indicated to PA.
Mr Hancock's comments come after the army was drafted in to help with the "challenges" of supplying personal protective equipment to NHS staff.
As frontline health workers face added pressures during the coronavirus pandemic, pictures emerged over the weekend of people interacting in crowds and at close quarters.
Mr Hancock told ITV News these people are delaying the solution to the outbreak.
"I think it’s very selfish of people who’ve chosen to interact socially with people that they don’t live with when the clear advice is not to do that," he said.
"You are helping to spread the virus and that costs lives, it’s obviously damaging to the NHS and it’ll mean that it’ll take longer to deal with this crisis and everyone wants this to be sorted."
He also warned any young people "who think that they’re invincible" that they are not - even if they are fit and healthy.
"The more that people flout the advice, the longer this is going to take to get through and I want us as a country to get through this as quickly as possible."
The Health Secretary earlier admitted there have been “challenges” with the supply of personal protective equipment to the NHS after a doctors’ leader said they felt they were being treated like “cannon fodder” and felt like "lambs to the slaughter".
Amid reports that a number of medics are seriously ill after becoming infected with Covid-19, including a nurse with no underlying health issues, Mr Hancock said the armed forces were being drafted in to help distribute PPE supplies to the health service.
He told Good Morning Britain deliveries were being made as he spoke.
Mr Hancock also told BBC Breakfast: “The challenge is that obviously the amount they are using has shot up and we need to get the distribution to get to every hospital and making sure they have got those masks.”
He said that a hotline has been set up so that medics can inform officials about where there are shortages.
“There is a huge logistical operation on because of the nature and the scale of the NHS and the sheer quantity of masks that are rightly being used.
“It is a massive effort and we want to know if you haven’t got the protective equipment or are about to run out - we want to hear from you as quickly as possible.
He spoke after the chair of the Doctors’ Association Dr Rinesh Parmar said: “We have had doctors tell us they feel like lambs to the slaughter, that they feel like cannon fodder.
"GPs tell us that they feel absolutely abandoned.
“We are all pleading with Boris Johnson that they really look into arranging the vital personal protection equipment that all of us need on the NHS front line.
“What our doctors are telling us is that although equipment is arriving, some of it is inadequate, some of it doesn’t meet the World Health Organisation guidance.”
Mr Hancock also said that 12,000 ventilators are now available after last week’s appeal by the PM, up from 5,000 that the NHS had access to previously.
His comments came after a letter in the Sunday Times from almost 4,000 NHS workers called on the Prime Minister to “protect the lives of the life-savers” and resolve the “unacceptable” shortage of protective equipment.
The British Association of Oral and Maxillofacial Surgeons has reported that some of the most seriously ill UK patients include healthy ENT (ear, nose and throat) specialists who ended up on life support after being infected by normal contact with patients.
Nurse and mother-of-three Areema Nasreen, 36, who has no underlying health issues, is also in intensive care in at Walsall Manor Hospital after being diagnosed with coronavirus.
NHS England said millions more items of PPE had been delivered over the last few days to hospitals, ambulance trusts and care homes among others.
It said the army would “play its part” from this week, offering personnel to “help to manage and offload supplies in busy NHS settings” and distributing PPE supplies to the front line.
Coronavirus: Everything you need to know
Mr Hancock said: “I am determined to ensure that the right kit gets to the right hospital, the right ambulance service, the right doctors’ surgery, right across the country.
“There have been challenges and I can see that.
"We’re on it and trying to solve all the problems.”
There has been increased pressure on the supply chain of PPE owing to the outbreak of Covid-19 as well as the related manufacturing slowdown particularly in China, the NHS said.