Prime Minister Boris Johnson is expected to confirm later the plan to lift almost all legal restrictions on social contact in England on 19 July.

But ahead of a news conference on Monday afternoon, Mr Johnson has urged people to be cautious.

"We must all take responsibility so we don't undo our progress, ensuring we continue to protect our NHS," he said.

He warned Covid-19 cases, currently at about 30,000 a day, would continue to rise as society reopened.

The PM's news conference will present the latest data, with Downing Street saying current modelling suggests hospital admissions, serious illness and deaths from Covid-19 will continue, but at a lower level than before the vaccination programme.

Number 10 said the delay in moving to the final stage of the roadmap out of lockdown, originally scheduled for 21 June, had allowed an additional 6.8 million first and second vaccine doses to be given out so far.

The government had also moved the expected end of restrictions closer to the school summer holidays, when transmission was likely to be lower, Downing Street said.

Mr Johnson said: "We are tantalisingly close to the final milestone in our road map out of lockdown, but the plan to restore our freedoms must come with a warning."

He said the vaccine rollout had weakened the link between infections, hospital admissions and deaths, but added the pandemic was "not over yet".

With cases set to rise as restrictions were lifted, "caution is absolutely vital", the prime minister said.

As well as the news conference, Health Secretary Sajid Javid is expected to announce the plans in Parliament.

The decision to remove restrictions is based on four tests, Downing Street said.

These are:

• continued progress in the vaccine rollout

• evidence that vaccination is reducing hospital admissions and deaths

• infection rates that do not risk unsustainable pressure on the NHS

• no new variants of concern which change the risks.

Dr Mike Tildesley, an expert in infectious disease modelling who sits on the government's Scientific Advisory Group for Emergencies (Sage), told BBC Breakfast the country was at a "tricky phase" and said "mixed messaging" from ministers over face masks was a concern.

He said: "I think it's actually quite confusing for people to know what the right thing to do is."

Care Minister Helen Whately has said she looked forward to not having to wear a face mask as much, while Chancellor Rishi Sunak said he would stop wearing one as soon as "legally possible".

But Health Minister Edward Argar said he would continue to carry a mask even if the legal requirement ended on 19 July as expected. He told BBC Radio 4's Today programme there would be "clear and strong guidance", with people having to make their own judgements on when to wear masks.

He added that rail companies could still impose their own requirements on mask-wearing once the national regulations ended.

Prof Peter Openshaw, who advises the government about viral threats on the Nervtag group, told the Today programme that masks "greatly reduce transmission", adding it was difficult to leave it up to individual judgement when "it is not only protecting yourself but also protecting other people".

He added the country was at a "crucial moment", with hospitalisations up 66% in the past week.

Dr Tildesley said that when some restrictions were lifted in May there had not been a significant uptick in the spread of the virus as many people had remained cautious, and he was hopeful that would remain the case after 19 July.

Nearly 45.9 million people - or 87.1% of adults in the UK - have now had at least one dose of a Covid-19 vaccine. Almost 34.8 million (two-thirds of adults) have had both doses.

On Sunday, the UK recorded another 31,772 confirmed coronavirus cases, along with a further 26 deaths recorded within 28 days of a positive test.

Although deaths remain relatively low, in the past seven days they rose by more than 66% on the previous week.

As well as ending legal requirements for face masks, the move to stage four of England's road map out of lockdown would mean there would no longer be any limits on how many people can meet and the 1m-plus rule would be lifted.

The changes on 19 July are also expected to mean nightclubs can reopen, pubs can serve people at the bar and capacity limits at concerts, theatres, sports events or places of worship would be lifted.

But the requirement to self-isolate if you are contacted by NHS Test and Trace will remain in place until 16 August, when it will be relaxed for people who have had both vaccine doses. If someone tests positive for the virus they will still be legally required to self-isolate.

Wales is due to review its restrictions on 15 July, while Scotland is expected to move to level 0 on 19 July and lift most legal restrictions on 9 August. Northern Ireland is due to ease some Covid measures on 26 July.