Former Ireland captain Paul O'Connell has retired from rugby on medical grounds with immediate effect, the lock announced on Tuesday.

"It is with deep regret that I have decided to retire from professional rugby following medical advice," O'Connell, 36, said in a statement published on the Irish Rugby website.

"I would like to take this opportunity to thank all at Rugby Club Toulonnais for their understanding and support over the past few months."

O'Connell, who won 108 caps for Ireland and seven caps for the British and Irish Lions, retired from international rugby late last year after a hamstring injury forced him out of the World Cup.

He had intended to see out his career with French Top 14 giants Toulon, having signed for them from Munster last year on a two-year contract, but his injury has forced him to abandon those plans without having played a single game for them.

"Since sustaining the injury at the World Cup I have been fully focused on returning to fitness and starting an exciting new chapter for both myself and my family in Toulon. Unfortunately this will no longer be possible," he added.

"I have been blessed to be a professional rugby player for over 14 years and to be part of Munster and Ireland teams that have experienced success.

"I have played with some of the best players to ever line out in the red of Munster and the green of Ireland and have had the privilege of captaining my country.

"I would like to thank those at Young Munster RFC, Munster Rugby, the IRFU (Irish Rugby Football Union) and Lions Rugby who have supported me over the course of my playing career."

O'Connell was part of the triumphant Lions tour of Australia in 2013 and also toured New Zealand in 2005 and South Africa in 2009, when he was captain.

He won three Six Nations titles with Ireland and two European Cups with Munster -- the only club he ever played for -- as well as the Celtic League three times.