Large parts of England will be placed under Tier 4 restrictions from Boxing Day, Dec. 26, the health secretary announced Wednesday amid rising coronavirus cases.

The new measures came as infections rose 57% across the country in the last week as a new variant of COVID-19 was discovered, Matt Hancock said.

The areas being placed under the strictest tier with lockdown-like restrictions are Essex, Norfolk, Sussex, Surrey, Oxfordshire and Hampshire.

Meanwhile, Bristol, Gloucestershire, Somerset, Swindon, the Isle of Wight, New Forest, Northamptonshire, Cheshire and Warrington will go into Tier 3, he said.

"The new variant makes everything much harder but we mustn't give up now," Hancock said.

After the discovery of a new variant, the British government has quickly changed its previous decision to relax gathering rules over the Christmas holiday.

Prime Minister Boris Johnson reduced the number of days people could meet over the festive period to only Christmas Day.

More than 40 countries have halted flights from the U.K. since last Saturday.

Hancock said there are two cases of another new variant in the U.K. and both cases had been in contact with cases who traveled from South Africa.

"We are incredibly grateful to the South African government for their science," he said, adding that the U.K. is quarantining new cases and placing restrictions on travel from South Africa.

Over 30,000 new cases have been recorded over the past three days since the authorities announced the new variant.

More than 68,000 people have died from COVID-19 in the U.K.