THE divisive debate on the future of Japan’s imperial family was suspended yesterday as politicians, foreign governments and ordinary Japanese welcomed the birth of the country’s first new prince for 40 years.

Just before 8.30am Princess Kiko, the wife of Emperor Akihito’s youngest son, gave birth by Caesarean section to a 2.6kg (5lb 7oz) baby boy. He becomes the third in line to the throne after his father, Prince Akishino and his uncle, Crown Prince Naruhito, after the birth of nine consecutive female children to the Emperor’s family.

The arrival of a boy derails plans to allow women to succeed to the throne, which were to have been put before Japan’s parliament, the Diet.

“It is better for us to warmly watch over [the baby] quietly for the time being,” said Junichiro Koizumi, the outgoing Prime Minister, who supported the idea of a reigning empress. “I think it is better for us to spend ample time to contemplate what the imperial family means . . . we’re not talking about submitting [the Bill] to the Diet next year or something like that.”

But he went on to make the point that historians and members of the imperial court had been quietly emphasising in the build-up to yesterday’s birth: that one male baby did not in itself ensure the survival of the imperial line.

“There is no guarantee that boys will always be born,” Mr Koizumi said. “So for the future I think succession to the throne will become rather difficult if female-line emperors are not accepted.”

But Taro Aso, his right-wing Foreign Minister — a candidate to replace Mr Koizumi — whose sister is married to a cousin of the Emperor, said that there was no hurry. “Now we may have about 40 years,” he said. “That will give us ample time for debate.” The 45-minute operation was straightforward and although nothing was seen of the mother and baby yesterday there was intense media coverage of the birth and the rituals that will follow it.

Apart from Prince Akishino, the infant prince’s other visitor was an emissary of the Emperor who presented him with a traditional gift — a handmade Japanese sword intended to protect the newborn against evil. Traditional gifts of a toy dog and doll will also be made.

Congratulations were sent from abroad, including a message from the Queen, President Chirac of France, the royal courts of Spain and Belgium, and the Government of Thailand, where Prince Akishino has spent much time pursuing a personal interest in the study of giant catfish.

Small groups of imperial enthusiasts gathered in front of the Imperial Palace bearing flags and shouting the traditional formula for congratulation “Banzai!”, which means “[may you live] Ten Thousand Years!”, and there were ingenious attempts to turn the happy event to commercial advantage. The Fujita Tourism Group is offering rooms at its hotels at the discounted rate of 2,500 yen (£11.40) a night — or about one yen for every gram of the new prince’s birth weight.

Companies selling baby products had seen spikes in their share prices in the weeks leading up to the births as investors speculated on a potential baby boom after the birth of the imperial child.

A report by Dai-ihi Life Research Institute predicted economic benefits of 150 billion yen (£683 million) from the birth, due to an increase in wedding ceremonies, honeymoons and births between the announcement of Kiko’s pregnancy and yesterday’s delivery. “Not only baby-related items, the celebratory mood may also loosen people’s purse strings in general,” said a company spokesman.

“This is a conservative estimate. The positive impact may be bigger on the back of the ongoing economic recovery in Japan,” he said.

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