Defending champion Blake ruled out of World C'ships

World 100 metres champion Yohan Blake will not defend his title at next month's World Athletics Championships in Moscow due to a nagging hamstring injury, his manager said on Tuesday.

The 23-year-old Jamaican suffered the injury at the Utech Classic in Kingston in April and missed last month's Jamaican trials but had qualified for the 100m in Moscow as defending champion.

"This decision was made after continual assessment and re-evaluations since his withdrawal from the Jamaican Senior Championships," Cubie Seegobin said.

"Yohan has made vast improvement, although the injury sustained in April of this year has prevented him from attaining the necessary fitness levels that we have grown accustomed to seeing in his competition performances."

Blake won the world 100m title in Daegu, South Korea, in 2011 following the disqualification of compatriot Usain Bolt for a false start.