The UK's coronavirus alert level has been raised to five - the highest possible - amid soaring infection rates and "immense pressure" on the NHS.

The nation has faced growing calls for a national lockdown in recent days to try and bring the virus under control, as a new strain sees Covid infections rise sharply in many parts of the country.

Coronavirus infection rates have almost doubled in a week in some areas of Suffolk and north Essex, latest public health data has revealed.

Prime minister Boris Johnson is due to address the country on television tonight to unveil harsher restrictions.

Ahead of Mr Johnson's statement, a joint statement from the UK's four medical directors said they were moving the country's alert level from four to five, following advice from the Joint Biosecurity Centre.

The statement went on to say: “Many parts of the health systems in the four nations are already under immense pressure.

"There are currently very high rates of community transmission, with substantial numbers of Covid patients in hospitals and in intensive care.

"Cases are rising almost everywhere, in much of the country driven by the new more transmissible variant.

"We are not confident that the NHS can handle a further sustained rise in cases and without further action there is a material risk of the NHS in several areas being overwhelmed over the next 21 days.

“Although the NHS is under immense pressure, significant changes have been made so people can still receive lifesaving treatment.

"It is absolutely critical that people still come forward for emergency care.

"If you require non-urgent medical attention, please contact your GP or call NHS 111.”