Spain's tallest basketball player Roberto Duenas announced his retirement on Monday at the age of 31 after 12 years as a professional.

Duenas, who is 2.21 metres tall, was discovered when a local basketball trainer spotted the giant 16-year-old waiting for a bus in the Madrid suburb of Fuenlabrada.

"He saw me at the bus stop and asked me if I wanted to play basketball and that's how it all started," Duenas told a news conference on Monday. "It has been a privilege to have been able to play and enjoy basketball."

Duenas, who played for Barcelona, Girona and Joventut, won six ACB league titles, one Euroleague, two King's Cups and a silver medal in the 1999 European championship. He also represented Spain in the 2004 Olympics in Athens.