Britain's Queen Elizabeth will not attend the COP26 climate change summit in Glasgow following medical advice to rest.
The 95-year-old monarch underwent preliminary medical checks in hospital last Wednesday after cancelling a visit to Northern Ireland.
She resumed public engagements on Tuesday by meeting ambassadors via video link from Windsor Castle, reports the BBC.
Buckingham Palace said she "regretfully" decided not to attend a reception at the summit.
But the palace said she would deliver her address to delegates using a recorded video message instead.
The Queen was due to travel to Scotland as part of a string of COP26 engagements by senior members of the Royal Family including the Prince of Wales, the Duchess of Cornwall and the Duke and Duchess of Cambridge between 1-5 November.
The other royals will still attend the summit.
It is understood that the monarch very much wants COP26 to result in meaningful action on climate change from participating nations, and hopes her absence will not be used by others as a reason not to attend.
The Queen was overheard at the opening of the Welsh Parliament earlier this month saying it was "really irritating" when people talk but don't act on climate issues.
Sir Peter Westmacott, a former UK ambassador to the US, said the cancellation was a "blow" to the summit but argued the substance of the talks should not be affected.
Speaking on BBC Radio 4's Today programme, he said the Queen's attendance would have been the "icing on the cake" but it was still a "very important opportunity" for Prince Charles to speak alongside other senior royals.
In photographs released on Tuesday, the Queen was seen smiling on camera as she greeted the South Korean and Swiss ambassadors, who were speaking to her from Buckingham Palace.
She also spoke to Chancellor Rishi Sunak by phone on Tuesday evening ahead of his Budget unveiling on Wednesday afternoon.
The photographed video call was the first time she had been seen since she hosted an investment summit at Windsor Castle on the evening of 19 October.
The following day, Buckingham Palace said the monarch had "reluctantly accepted medical advice to rest for the next few days".