Keir Starmer, the leader of Britain's opposition Labor Party, said he was deeply concerned about news from Buckingham Palace that Queen Elizabeth's health had declined.

"Along with the rest of the country, I am deeply worried by the news from Buckingham Palace this afternoon," he said in a statement.

"My thoughts are with Her Majesty The Queen and her family at this time, and I join everyone across the United Kingdom in hoping for her recovery," he added.