Former Manchester United defender Jaap Stam has announced his retirement from football with immediate effect.

The 35-year-old, now with Ajax, revealed that he had taken the decision to quit due to a lack of motivation.

"This decision was not taken overnight," said Stam, who retired from international football with Holland three years ago having won 67 caps, at press conference at Ajax's Amsterdam Arena.

"A while ago, I told [technical director] Martin van Geel and [managing director] Maarten Fontein that I could no longer motivate myself enough. Physically, I was no longer 100%.

"During matches, I was more busy with myself than with the opponent. That's not right. Especially for someone who relies on his strength.

"I want to give myself for the full 100% and not 60% or 70%."

Stam began his career in the 1992-1993 season at FC Zwolle, and later represented Cambuur Leeuwarden, Willem II and PSV Eindhoven, where he played for three seasons.

In 1998 he signed for Manchester United, going on to win three league titles, the FA Cup and the Champions League under Sir Alex Ferguson.

He left United in acrimonious circumstances in 2001 after falling out with Ferguson following the publication of the Dutchman's autobiography.

Stam subsequently spent five years in Italy with Lazio and AC Milan before returning to his homeland to sign for Ajax in the summer of 2006.