PARIS, France - Warm words of congratulations poured in from around the world for Britain's Prince William and his wife Kate following the birth of their first baby, a boy destined to become king.
US President Barack Obama and his wife Michelle led tributes to the "joyous occasion", wishing the new parents "all the happiness and blessings parenthood brings."
The Duchess of Cambridge gave birth to a healthy male heir weighing 8lbs 6oz (3.8 kilos) in London on Monday.
"Given the special relationship between us, the American people are pleased to join with the people of the United Kingdom as they celebrate the birth of the young prince," the president said in a White House statement.
As Britain waited to catch its first glimpse of the newborn, Russian President Vladimir Putin offered his well-wishes to the British monarch on the birth of her third great-grandchild.
Putin "congratulated Queen Elizabeth II on the birth of her great-grandson and wished strong health for the newborn, the Duchess of Cambridge and all the members of the Royal Family," the Kremlin said in a statement.
Singapore Prime Minister Lee Hsien Loong took to Facebook to congratulate the Duke and Duchess of Cambridge "as they begin on the new and exciting journey of parenthood".
The as yet unnamed royal baby automatically becomes third in line not only to the national throne but to the 15 other Commonwealth realms that have the British monarch as their head of state.
Australian Prime Minister Kevin Rudd called it "a happy day for our close friends in Britain and the Commonwealth", while New Zealand Prime Minister John Key said it was "wonderful news".
Support for the royals in both countries remains strong, although debate flares periodically about whether ties to the monarchy should be cut.
Canadian Prime Minister Stephen Harper meanwhile tweeted: "On behalf of all Canadians, I offer our heartfelt congratulations to the Royal Couple & the entire Royal Family."
Canada, the country William and Kate visited on their first official foreign trip after marrying, bathed part of the Niagara Falls in blue light to mark the birth of the baby boy.
Across the pond from Britain, French President Francois Hollande sent his "warmest wishes of joy and happiness" to Kate and William.
"The happy news of the birth of the prince has delighted the French people," he said in a letter to the young couple.
In a separate message to the queen, Hollande stressed the good relationship between the two EU members.
"The Prince will one day be called on to reign and to follow in the footsteps of his ancestors, who -- since the Entente Cordiale -- have contributed to developing excellent ties between our two countries."
Israeli President Shimon Peres wished "a hearty Mazel Tov" to the royal family for a baby "born in the most democratic country on earth".
"May he live to a hundred and twenty years," Peres wrote on Facebook, adding a picture of a gift for the parents, a blue-and-white baby suit embroidered with the words "From Israel with Love".
Japan added its voice to the chorus of global well-wishes, with Prime Minister Shinzo Abe sending a congratulatory message to British Prime Minister David Cameron.
"We wish the son the best of health. We hope that with this event, Japanese people will feel closer to Britain," chief Cabinet Secretary Yoshihide Suga told a news conference in Tokyo.
Even Iran got in on the act, with Tehran setting aside differences with Britain over its disputed nuclear programme to congratulate the royals.
"I congratulate Her Majesty, the Queen of England, and also the Crown Prince on the birth. This is a source of happiness," foreign ministry spokesman Abbas Araqchi told reporters in Tehran.
Celebrities too rushed to comment on the new arrival.
"It's a boy! So happy for my cousin Kate and the future King of England!" tweeted US talk show host Ellen DeGeneres, recently informed by the New England Genealogical Society that she is indeed a distant relative of the future queen.
Fellow funny lady Joan Rivers quipped: "Congratulations to Kate & William on the birth of their baby boy! So relieved that his name won't include the words Ivy or Apple."