Faith leaders across the UK have expressed their concern and offered prayers for The Queen after doctors said Her Majesty's health was giving cause for concern.
The Archbishop of Canterbury, Justin Welby said: "My prayers, and the prayers of people across the Church of England, and the nation, are with Her Majesty The Queen today. May God's presence strengthen and comfort Her Majesty, her family, and those who are caring for her at Balmoral."
Cardinal Vincent Nichols, Archbishop of Westminster and head of the Catholic Church in England and Wales, expressed his concern. He said "May the blessings of the Lord strengthen and comfort her and her family."
In a statement the Muslim Council of Britain has wished the Queen a "swift and lasting recovery" and offered prayers for the monarch and the Royal Family.
The UK's Chief Rabbi has expressed similar sentiments, saying the Queen "is very much in my prayers today".
Ephraim Mirvis, Chief Rabbi of the United Hebrew Congregations of the Commonwealth, said: "I know that Jewish communities around the Commonwealth will join me in wishing her a full and swift recovery."
Special prayer services are taking place today in churches across the UK.