Japanese old and young celebrated the birth date Monday of cartoon character Astro Boy, who was recognised as an envoy by one Tokyo borough and resident of a town north of the capital.

"The birthday" of the popular robot boy, known as "Atom" in Japan, was set half a century into the future on April 7, 2003 by comic-strip legend Osamu Tezuka when his creation first appeared in a comic book in 1951.

Hiroko Nakayama, mayor of Tokyo's Shinjuku Ward, named Astro Boy as its "ambassador for the future" in a ceremony attended by an actor in an Astro Boy costume.

"Please grow up with our children and guide them to their dreams," she said.

The robot boy was supposed to have come to life at a laboratory in Takadanobaba, Shinjuku Ward.

Hundreds of citizens queued up at Takadanobaba Post Office, which marked the day by stamping a picture of Astro Boy flying on letters and cards.

Niiza City north of Tokyo registered the fictional character as a resident as the city houses Tezuka Productions Co. Ltd., which produces new episodes of Astro Boy. The cartoon returned to television screens in Japan Sunday.

The city will hand out copies of his resident registration to the first 10,000 people to ask for it.

After his comic book debut in 1951, Astro Boy was the star of Japan's first domestically-produced television cartoon show in the early 1960s, and his endeared himself to another generation with the broadcast of a second series in colour in the early 1980s.

The cartoons have been broadcast in more than 40 countries outside Japan since first being aired in the United States in 1963.