Prime Minister Boris Johnson is set Monday to confirm "Freedom Day" next week with the lifting of most pandemic curbs in England, but will urge caution with experts worried the government is moving too fast.

Johnson was due to hold an afternoon news conference confirming that the government's tests have been met to allow a full reopening of the economy on July 19, doing away with the final measures of a months-old lockdown. 

But with Britain now averaging more than 30,000 daily cases of the fast-spreading Delta coronavirus variant, scientists are fretting that the ending of measures such as mandatory mask-wearing spells trouble.

And the government's decision to allow more than 60,000 football fans to attend Sunday's European Championship final between England and Italy has added to the fears, after near-total flouting of distancing rules.

Johnson, however, insists the time is right to move from legally enforced rules to personal responsibility, and use the summer months to prepare for a potentially more damaging wave of Covid-19 in the winter.

"We are tantalisingly close to the final milestone in our roadmap out of lockdown, but the plan to restore our freedoms must come with a warning," he said in remarks previewing the announcement.

"While the phenomenal vaccine rollout has offered every adult some protection against the virus, and the crucial link between cases, hospitalisations and deaths is weakened, the global pandemic is not over yet.

"Cases will rise as we unlock, so as we confirm our plans today, our message will be clear," Johnson said.

"Caution is absolutely vital, and we must all take responsibility so we don't undo our progress, ensuring we continue to protect our NHS (National Health Service)."

While infection rates have jumped, deaths remain relatively stable in Britain after a mass vaccination campaign, and right-wing media are acclaiming July 19 as "Freedom Day".

But there are signs the campaign is petering out, with take-up rates among younger adults waning. 

Sarah Clarke, a board member of the UK's Faculty of Intensive Care Medicine, said there had been a 60 percent increase in ICU admissions over the past week and "we have over 500 patients being admitted per day into intensive cares".

"I would absolutely err on the side of extreme caution," she told Times Radio about Johnson's plan to end rules on masks and social distancing in England.

Keeping the public safe is "not sustainable if we all decide to take our masks off and think that the vaccine programme no longer applies".

The UK's other nations -- Scotland, Wales and Northern Ireland -- set their own health policy and are moving more cautiously.