Former world record holder Asafa Powell has insisted he will be fit to run at the Olympic Games after withdrawing from the London Grand Prix with a groin strain.

The Jamaican was due to face Tyson Gay of the United States over 100 metres at Crystal Palace on Friday, but has now pulled out of the event for the second year in a row.

"I've been carrying some soreness in my groin since the Olympic trials and have been unable to train at 100 percent," Powell said.

"I need to ensure I'm ready for the Games and cannot take any risks," the 29-year-old added as vowed to be fit for the Olympics in the British capital by saying: "I will be ready in August."

However, the Olympic relay gold medallist made similar comments 12 months ago when he also missed the London Diamond League race with a groin injury which kept him out of the subsequent World Championships in South Korea.

He said then: "I am focusing on Daegu and as much as I'd like to run tonight, I just can't take the risk with the major championships three weeks away."

Powell is the fourth fastest man in the world this year behind compatriots Yohan Blake and Usain Bolt and US sprinter Justin Gatlin.

He has run under 10 seconds more than 80 times in his career, but never won an individual title at a major international championship, finishing fifth in the Olympic 100m final in both the last two Games, in Athens and Beijing.