"Her Majesty is disappointed not to attend the reception but will deliver an address to the assembled delegates via a recorded video message."
The palace shared no further details about the Queen's health scare or if the decision was made because her condition had changed in some way.
It was previously reported that Her Majesty was hoping to be able to attend the summit despite her recent health scares.
"She is fine, but she needs the rest — she is saving her energy for Cop [Cop26]," a source told The Times.
A number of other key royals, including Prince Charles and Prince William, are still set to attend the climate change summit despite the Queen's absence.
There have been concerns for the 95-year-old since she pulled out of another royal event last week on medical advice.
Her Majesty was supposed to travel to Northern Ireland on Wednesday for a royal visit but "reluctantly" cancelled the trip at the last minute on doctor's orders.
It was later revealed that she was admitted to hospital that same day and stayed overnight for practical reasons, before returning to Windsor on Thursday.
WATCH BELOW: The Queen arrives for the funeral Of Prince Philip
She then skipped attending a local church service on Sunday, sparking more concern among the general public, and carried out royal duties virtually on Tuesday.
"Today The Queen received two Ambassadors in audience via video link from Windsor Castle," read a post on the Royal Family Twitter account alongside a photo of the Queen at work.
The picture shows Her Majesty sitting in front of a large computer monitor as she spoke with the ambassadors remotely.
It's understood she will use a similar setup to virtually address the Cop26 summit next week.
After the sad death of Prince Philip, aged 99, in April, some royal watchers are fearful that these recent scares could indicate a sharp decline in the Queen's health.
Though the 95-year-old has kept up a busy royal schedule in recent years and is set to mark 70 years on the throne next year, the public are still worried.
Reports suggest that key royals like Charles and William have stepped up their royal duties to take some of the pressure off the Queen in her final years.
Meanwhile, palace aides are said to be cutting back on Her Majesty's upcoming engagements and she will now be accompanied by another royal to all events, in case she needs to pull out at short notice.
This story originally appeared on our sister site, Now To Love.