The Queen has postponed a diplomatic reception at Windsor that was due to be held on Wednesday.
Buckingham Palace said Her Majesty had accepted the foreign secretary's advice to delay the event, which would have seen her meet hundreds of members of the Diplomatic Corps.
It is understood the postponement is because of the conflict in Ukraine.
In a statement, the palace said: “The Queen has accepted the foreign secretary's advice that the diplomatic reception at Windsor on March 2 should be postponed.”
The Queen has cancelled several engagements since testing positive for Covid-19 last Sunday.
On Thursday, the Palace announced that she had postponed two scheduled virtual audiences but will continue with light duties.
The nation’s longest-reigning monarch fell ill weeks after reaching her historic Platinum Jubilee of 70 years on the throne on 6 February.
She carried out her first major public engagement for more than three months on 5 February, when she met charity workers at Sandringham House, cut a celebratory cake and used a walking stick to rest on.
The Queen is understood to be triple vaccinated, but she had been on doctors’ orders to rest since mid- October after cancelling a run of engagements and spending a night in hospital undergoing tests.
She is believed to have spent time with Charles on Tuesday 8 February, when he hosted an investiture at her Windsor Castle home. He tested positive for Covid a few days later, but made a quick recovery.
Extravagant celebrations for the Queen’s Platinum Jubilee are set to begin in May.
Additional reporting by agencies
