Public figures have sent best wishes and concerns to the Queen after Buckingham Palace announced that she is under medical supervision and doctors are concerned for her health.
Members of her family have rushed to be by her side amid serious health fears for the nation’s longest-reigning monarch.
The monarch, 96, pulled out of a virtual Privy Council on Wednesday, a day after appointing Liz Truss as PM at her home in the Scottish Highlands.
A Palace spokesman said that the Queen remains “comfortable”.
Well-wishes have now been sent by several politicians and public figures.
The prime minister said: “The whole country will be deeply concerned by the news from Buckingham Palace this lunchtime.
“My thoughts – and the thoughts of people across our United Kingdom – are with Her Majesty The Queen and her family at this time.”
Labour leader Sir Keir Starmer said he is “deeply worried” by the news from Buckingham Palace and he is hoping for the Queen’s recovery.
Watch: Commons speaker sends 'best wishes' to Her Majesty the Queen
He tweeted: “Along with the rest of the country, I am deeply worried by the news from Buckingham Palace this afternoon.
“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.”
The news was announced to MPs by Commons speaker Sir Lindsay Hoyle during Truss’s statement on energy prices.
In a short statement, Hoyle said the the whole House "sends our best wishes" to the Queen.
Leader of the House Penny Mordaunt said: "I know this news will be greeted with concern and sadness by us all. My thoughts are with Her Majesty the Queen and her family."
Former Conservative prime minister David Cameron said he was “deeply concerned” by the news.
“Deeply concerned by the news this afternoon from Buckingham Palace,” he tweeted.
“I send my heartfelt thoughts and prayers to Her Majesty The Queen and the Royal Family at this worrying time.”
The Archbishop of Canterbury said the “prayers of the nation” are with the Queen, adding: “May God’s presence strengthen and comfort Her Majesty, her family, and those who are caring for her at Balmoral.”
Scotland’s first minister Nicola Sturgeon said: “All of us are feeling profoundly concerned at reports of Her Majesty’s health.
“My thoughts and wishes are with the Queen and all of the royal family at this time.”
Welsh first minister Mark Drakeford said in a tweet: “Concerned to hear the news from Buckingham Palace.
“I send my best wishes to Her Majesty and her family on behalf of the people of Wales.”
Former PM Tony Blair said: “It is deeply concerning to hear today’s news from Buckingham Palace.
“My thoughts and prayers are with Her Majesty the Queen and her family at this worrying time.”