Millions of Britons will endure another four weeks of lockdown amid fears the Delta variant could lead to a third coronavirus wave.

England was due to come out of lockdown on June 21, but Prime Minister Boris Johnson has pushed the date back to July 19.

In his announcement on Tuesday morning (Australian time), Mr Johnson said cases were growing by about 64 per cent a week and the number of people in hospital intensive care was rising.

He cited the risk of spiking hospital admissions from the Delta variant as a reason to delay lifting all restrictions on social contact.

That means pubs, restaurants, nightclubs and other hospitality venues won’t be able to fully reopen for another four weeks.

Restrictions that will remain

• Pubs limited to providing table service to groups of up to six, with no one allowed to drink or stand at the bar;
• Only six people or two households can gather indoors;
• Cinemas and theatres are limited to a capacity of 50 per cent;
• Nightclubs remain closed;
• A limited audience of 1000 people at sporting events.

In an attempt to soften the blow, Mr Johnson axed the 30-guest limit at weddings in England.

He hopes delaying his plans to lift lockdown restrictions by a month will speed up Britain’s vaccination program – already one of the world’s furthest advanced.

“I think it is sensible to wait just a little longer,” Mr Johnson said.

“On the evidence that I can see right now. I’m confident that we will not need more than four weeks.”

The situation will be reviewed on June 28, which could allow the reopening being brought forward. However, Mr Johnson’s spokesman said this was considered unlikely.

In recent weeks there has been rapid growth in new COVID infections caused by the Delta variant, first discovered in India.

Health officials believe it is 60 per cent more transmissible than the previous dominant strain and scientists have warned that it could trigger a third wave of infections.

On Monday, Britain had 7742 new COVID-19 cases and three deaths.

-with AAP