Veronica Campbell-Brown, far right, powers home [GALLO/GETTY]

Jamaica has made a clean sweep of Olympic sprint golds with victory in the women's 200 metres shutting out athletics giant the United States.

Veronica Campbell-Brown powered down the back straight after taking a metre's lead by the halfway mark.

Her face, creased with pain, broke into a broad grin at the finish, where she dropped to her knees for a prayer.

Campbell-Brown also won the event in 2004.

American world champion Allyson Felix came second and 100 metre silver medallist Kerron Stewart of Jamaica came third.

The victory will bring more rejoicing to an island already exultant over the two world records and double sprint gold of Usain "Lightning" Bolt.

'More respect'

Bolt, 22 on Thursday, collected his second gold in a rain-soaked ceremony in the Bird's Nest stadium and gave his signature lightning bolt gesture for the cameras.

The head of the International Olympic Committee (IOC) has questioned the Jamaican's sportsmanship, taking exception to his exuberant celebration of his 100 metre win on Saturday when he pounded his chest even before crossing the finish line.

"I think he should show more respect, shake hands, give a tap on the shoulder to the other ones. Not making gestures like the one he made," Jacques Rogge said.

"He still has to mature."

Jamaican coach and former sprinter Don Quarrie defended Bolt, saying his celebrations were just youthful high spirits, from a man who is "playful, funny, happy".

The United States have won a major sprint medal at every games since 1984 and this year's collection of silvers and bronzes will be little consolation for a team doing worse than anticipated in track and field, a traditional strength.

They were further humiliated when the men's team dropped the baton during the heats of the 4x100 metre relay, knocking them out.