Britain's Queen Elizabeth has been advised by her doctors to rest for at least the next two weeks, with the 95-year-old monarch avoiding official visits and only undertaking light duties during this time, palace officials said on Friday.

However the queen, the world's oldest and longest-reigning monarch, is determined to appear at the annual Remembrance Sunday service that commemorates the nation's war dead on Nov. 14, Buckingham Palace said.

Elizabeth stayed overnight in hospital last week after undergoing "preliminary investigations" for an unspecified ailment that is not related to COVID-19.

The monarch had already pulled out of addressing world leaders in person next week at the COP26 climate change summit in Glasgow. A palace source said she remained in good spirits and had recorded a video address for the delegates on Friday afternoon.

Following the latest advice, Elizabeth will no longer attend a major event on Nov. 13 hosted by a British military charity. But the queen had a "firm intention" to be present at the main national service of remembrance for veterans on Sunday Nov. 14, the palace said.

Further rest for the queen was a "sensible precaution," a palace source added.

The queen appeared in a cheerful mood in video footage released by the palace on Thursday, when she took part in a ceremony awarding a medal for poetry.

She has also been shown greeting foreign ambassadors via video link.

Elizabeth, who is queen of 15 other realms including Australia, Canada and New Zealand and next year celebrates 70 years on the throne, has been known for her robust health and still carries out many public duties.

The evening before she had to go into hospital, she hosted a drinks reception at Windsor Castle for billionaire business leaders, including Bill Gates, who were attending a green investment conference ahead of COP26.