LONDON (AFP) - Sprint superstar Usain Bolt won the 100m at the London Grand Prix here on Friday in astounding style on a day when it was announced five of his fellow Jamaicans had tested positive for drugs.

Despite running into a stiff head wind, world record-holder Bolt, the Olympic 100m and 200m champion, still clocked a time of 9.91sec even though he clearly slowed down in the closing stages.

Bolt, who in Beijing last year set a world record of 9.69sec while winning gold, was not the quickest away from the start but once he was into his stride no-one in final at the Crystal Palace track in south London ever looked like catching him.

It was a display to worry rivals ahead of next month's World Championships in Berlin but Bolt, who finished second in his heat, told the BBC afterwards: "I am ready for.....