Berlin (AFP) - Ukraine's former heavyweight champion Wladimir Klitschko announced his retirement from boxing on Thursday.

Klitscko hangs up his gloves as one of the all-time greats in the ring after a nine-and-a-half year reign as heavyweight champion.

His last fight was in April when he was stopped by England's Anthony Joshua in the 11th round of the World Boxing Association title fight at Wembley Stadium in London.

"I never thought I'd have such a long and successful sporting career, I thank you all from the bottom of my heart," he told his fans in a statement.

"I have achieved everything I dreamed of, and now I want to start my second career after sports," said Klitschko.

His retirement dashes a mooted blockbuster rematch with Joshua possibly in Las Vegas in November.

Klitschko, who won the super-heavyweight gold at the 1996 Atlanta Olympic Games, held the unified title from 2006-2015 before losing to British boxer Tyson Fury in 2015.

He bows out with a record of 64 wins and five defeats.