LONDON (REUTERS) - Britain reported its highest number of new Covid-19 cases in more than six months on Friday (July 16), days before the government plans to relax curbs on pubs, restaurants and nightclubs in England and ease requirements to wear masks.

Government data showed there were 51,870 new cases of coronavirus, up from 48,553 on Thursday and the highest daily total since Jan. 15.

The number of new deaths reported as having occurred within 28 days of a positive Covid-19 test was 49, down from 63 on Thursday, taking the total on this measure to 128,642.

However, with over two thirds of the adult population fully vaccinated, Prime Minister Boris Johnson has said the time is right to lift most remaining restrictions, due to a weaker link between case numbers and subsequent hospitalisation or death.

Friday's data showed 67.5 per cent of British adults had received two vaccine doses, while 87.6 per cent had received at least one dose.

Most of those who are unvaccinated are younger people who only gained access to vaccines recently.

From Monday nightclubs in England can reopen and pubs, bars and restaurants will be able to pack in more customers.

A legal requirement to wear masks on English public transport and in shops will also go, although many transport operators and stores have said they will require or strongly advise customers and passengers to continue doing so.

The government's chief medical adviser, Dr Chris Whitty, warned earlier on Friday that England could quickly slip back into crisis.

"I don't think we should underestimate the fact that we could get into trouble again surprisingly fast," he said.