The monarch, 95, is experiencing mild cold-like symptoms and expects to continue light duties at Windsor this week, the palace said.

She is understood to be triple vaccinated.

COVID news live: Messages of support for Queen pour in

The Queen was in direct contact with Prince Charles the week the heir to the throne tested positive for COVID for the second time.

The announcement was made just a few weeks after the Queen, Britain's longest-reigning monarch, reached her historic Platinum Jubilee of 70 years on the throne.

'Mild cold-like symptoms'

A statement by Buckingham Palace said: "Buckingham Palace confirm that The Queen has today tested positive for Covid.

"Her Majesty is experiencing mild cold-like symptoms but expects to continue light duties at Windsor over the coming week.

"She will continue to receive medical attention and will follow all the appropriate guidelines."

The Royal Household has its own royal physicians and the Queen's doctors will be on hand to take care of and monitor her health.

Professor Sir Huw Thomas, head of the Medical Household and Physician to the Queen, is expected to be in charge.

The Queen is believed to have spent time with Prince Charles on 8 February at Windsor Castle - a few days later he tested positive for the virus but made a quick recovery to full health.

The Duchess of Cornwall also tested positive.

Messages of support pour in for Queen

The chair of the Conservatives and leader of the Labour party are among those to send well-wishes to the Queen.

Sir Keir Starmer said: "On behalf of myself and the whole of @UKLabour, wishing Her Majesty The Queen good health and a speedy recovery. Get well soon, Ma'am."

MP Oliver Dowden tweeted: "Wishing Her Majesty the Queen a swift recovery."

London Mayor Sadiq Khan added: "The commitment Her Majesty the Queen has shown to our country continues to be unwavering.

"Wishing her a swift and safe recovery from COVID-19."

Monarch on doctors orders to rest since mid-October

The COVID diagnosis will cause concern, given the Queen's advanced age and her health scare in recent months.

She has been on doctors' orders to rest since mid-October when she cancelled a run of engagements and spent a night in hospital undergoing preliminary tests.

The monarch carried out her first major public engagement for more than three months on Saturday, 5 February, the eve of her Jubilee when she met charity workers at Sandringham House and cut a celebratory cake.

Over Christmas, the Queen cancelled her annual family gathering at her Norfolk estate amid rising Omicron cases in the UK.

It was the Queen's first Christmas period without the Duke of Edinburgh, her husband of more than 73 years, who died on 9 April last year.

She returned to Windsor in early February.