Chief Rabbi Ephraim Mirvis led tributes to the Duke and Duchess of Cambridge as they celebrated the birth of a baby son on Monday.
The new arrival was born at at St Mary's Hospital, London at 11.01am, weighing 8lb 7oz, Kensington Palace confirmed.
In a message on Twitter Chief Rabbi Mirvis said: “Congratulations to the Duke and Duchess of Cambridge and to the entire Royal Family on the birth of a beautiful baby boy!
“We wish their Royal Highnesses many years of joy from their new son. May he be a source of blessing for our country all the days of his life. Mazaltov!”
In a further Twitter message the Board of Deputies said: “A hearty mazal tov to the Duke and and Duchess of Cambridge on the birth of a baby”.
Simon Johnson, Chief Executive of the Jewish Leadership Counci issued a statement wishing the couple “a hearty mazal tov on the arrival of their new baby boy. It is wonderful and joyous news and the whole community celebrates with Their Royal Highnesses.”
Reform Judaism’s Senior Rabbi Laura Janner-Klausner and Liberal Judaism’s Director of Strategy and Partnerships Rabbi Charley Baginsky both congratulated the Royal couple on behalf of Britain’s Progressive Jewish movements.
They said: “The birth of a child reminds us of the miracle of life and the many opportunities for optimism. We wish the couple, Prince George, Princess Charlotte and all the Royal Family, mazel tov.”
Meanwhile Israel’s president Reuven Rivlin also sent his congratulations, saying: “Mazal Tov! Congratulations to TRH the Duke & Duchess of Cambridge on the birth of their son Royal Baby. Together with Nechama, and all the Israeli people, I send warmest wishes to Her Majesty the Queen, & all the Royal Family. Looking forward to welcoming the Duke to Israel soon.”
The baby is fifth in line to the throne, the Queen and the Duke of Edinburgh’s sixth great-grandchild and a younger sibling of Prince George and Princess Charlotte.
A Kensington Palace statement said Catherine and her son, who is yet to be named, are "both doing well".
Members of both families had been informed and were "delighted with the news".
Kensington Palace said the name of the baby would be announced in due course while a formal notice of the birth had been posted on the forecourt of Buckingham Palace.
Favourite names at the bookmakers include Arthur, Albert, Frederick, James and Philip.