The International Olympic Committee voted unanimously for the proposal which applies only to the Tokyo Games, where 33 sports will now be contested.

"This is really a milestone in the innovation of the Olympic programme which we can then experience in four years from now in Tokyo 2020," IOC president Thomas Bach told delegates in Rio de Janeiro.

The five extra sports -- with women-only softball bracketed with baseball -- make up 18 events and 474 athletes in the Tokyo roster, and give it a strong experimental flavour.

IOC members voted 85-0 in favour but not before some concerns were raised about baseball, whose US-based stars are not confirmed for the Games.

"At this moment we are not sure that in the days of the baseball competition in Tokyo... that the athletes playing in the United States can take part," said Franco Carraro, chairman of the working group which oversaw the package.

"We hope that the international federation reach an agreement with the United States professional league, as happened with basketball and ice hockey," he added.

"If not, the competition of baseball will not fulfil completely and perhaps if we accept baseball for 2020 it will be difficult for baseball to be included in the future."

Wednesday's rubber-stamping ends a more than a year-long process which whittled down 26 applications and dropped squash, bowling and wushu -- a Chinese martial art -- from an eight-sport shortlist in September.

Baseball is a natural choice for Japan, where it is the number one sport and has produced stars like Ichiro Suzuki and Hideki Matsui. Its inclusion is estimated to reap an extra $50 million in ticket sales.

Surfing chiefs highlighted the sport's "sex appeal" during their campaign. Initial plans to compete on an artificial wave have been dropped in favour of holding the event on the coast south of Tokyo.

Climbing flagged up its rugged, windswept image, the roller sports federation promised NBA-style razzmatazz, and karate gathered 720,000 signatures from around the world backing its Olympic bid.

The IOC scrapped a short-lived cap of 28 Olympic sports to include the new events. In Rio, golf and rugby return to the Olympic progamme after a gap of 112 years and 92 years respectively.

Appealing to new generations has become a preoccupation of Olympics organisers as audiences splinter and the appeal of traditional sports like athletics and swimming wanes.

The Olympics body is spending 446 million euros (US$499 million) on a new 'Olympic Channel', which will broadcast footage and stories from the Games on the internet from August 21, the day Rio closes.