TOKYO - Japan's double Olympic breaststroke champion and former world record holder Kosuke Kitajima has been working hard in a bid to retain his titles at the 2008 Beijing Olympics, Kyodo News said Wednesday.

Japan's Kosuke Kitajima is applauded as he leaves the award ceremony for the men's 4x100m medley relay swimming finals competition at the Asian Games in Doha December 7, 2006. Japan took the gold medal. [Reuters]

Kitajima returned to Tokyo on Wednesday after a month's training in Arizona, the United States, at an elevation of over 2,000 meters.

"Last year I didn't have any good records, so I was somewhat concerned, but I really dug in deep with a good training this time out," he was quoted as saying.

Kitajima's short-term goal is the world championships in Melbourne from March 17 through April 1. His main goal, the report said, is to excel his American rival, the world record holder Brendan Hansen.

"I've started to get excited racing with him (Hansen) again. I'm confident about the challenge," Kitajima said.

At the Athens Olympics in 2004, Kitajima won the 100 and 200 meter golds, with Hansen settling for silver in the 100 and bronze in the 200. However, Hansen has performed better than Kitajima since then.