'Right time': James Magnussen announces sudden retirement at 28

Two-time swimming world champion and Olympic silver-medallist James Magnussen has retired from competitive swimming.

The 28-year-old Magnussen called time on his career in the pool on Wednesday with 15 major event medals to his credit.

He won silver in the men's 100m freestyle at the 2012 London Olympics, touching just behind American Nathan Adrian, and won the men's 100m freestyle at the 2011 and 2013 World Championships.

He also won two gold medals - in the men's 100m freestyle and 4x100m freestyle relay - at the 2014 Glasgow Commonwealth Games, as well as gold in the latter event at the 2010 and 2018 Games.

But "The Missile" has suffered recurring shoulder issues in recent years, undergoing surgery in 2015, and felt ready to hang up the cap.

"At 28 years of age I feel I could have swum at another Olympic Games, but with the lofty standards I have held myself to over the years and the high expectations I have, I believe now is the right time to step away from the sport," the Port Macquarie native said.

"I have enjoyed every moment and every experience, good or bad, and it has shaped the man that I am today.

"I have always been proud to stand on the starting blocks representing my family, my friends and my country. There is no greater honour or responsibility."

Last year, Australian head coach Jacco Verhaeren admitted Magnussen was a "50-50" chance of retiring after skipping Pan Pacs trials.

Swimming Australia President John Bertrand AO congratulated Magnussen for his career exploits.

"He should be very proud of what he has achieved - very few people in the world have reached these heights in competitive sport," Bertrand said.