Beijing - Veronica Campbell-Brown completed a men's and women's 100 and 200 metres gold medal sweep for Jamaica at the Beijing Olympics with an emphatic 200m victory on Thursday as rivals United States dropped the baton in both sprint relays.

The 100m world champion Campbell-Browne clocked 21.74 seconds to beat Allyson Felix, the US world champion over 200m, who had to settle for silver in 21.93. Bronze went to Jamaican 100m silver medallist Kerron Stewart in 22.00.

Campbell-Browne's time was the fastest since Gwen Torrence ran 21.72 in the semi-finals at the Barcelona Olympics in 1992.

Jamaica ruled the sprints in Beijing, with Usain Bolt winning both men's races in world record time and Shelley-Ann Fraser leading a Jamaican sweep of the women's 100m medals.

The Jamaicans are also well-positioned to win the 4x100m sprint relays as neither the American men nor the women managed to execute the final baton exchange.

First Darvis Patton and three-time world champion Tyson Gay dropped the baton and the women did the same in the handover from Torri Edwards to Lauryn Williams.

The men's 2004 gold medallists Britain were also disqualified as only 10 of 16 men's teams were ranked.

Barbora Spotakova of the Czech Republic saved the best for last as she captured women's javelin gold with a last attempt throw of 71.42m, a European record and just 28cm short of the world record from Cuba's Osleidys Menendez.

Mariya Abakumova got silver for Russia with 70.78m (which lasted only 20 minutes as the continental record). Christina Obergfoell of Germany, who was the continental record holder until Thursday, took bronze with 66.13m

The other evening finals were the men's 400m, 110m hurdles and triple jump.

Earlier, world champion Olga Kaniskina of Russia led from start to finish to win the women's 20 kilometres race walk gold in 1 hour 26 minutes 31 seconds in driving rain on a course outside the Bird's Nest stadium.

Kjersti Platzer of Norway got the silver as at Sydney 2000 in 1.27:07 and then took almost longer to find a Norwegian flag in the stadium for her lap of honour. Elisa Rigaudo claimed bronze for Italy in 1:27:12 hours.

"I have won at championships but an Olympic medal is more difficult because all the competitors are here. I was in good condition," said Kaniskina.

The walkers were undeterred by the rain.

"The weather had no influence on me. It was better than a sunny and hot day," said Kaniskina. Platzer agreed: "For endurance athletes rain doesn't matter."

The decathlon got underway with American favourite Bryan Clay taking an early lead with a 100m run in 10.44 seconds, a long jump of 7.78m and a personal best shot put of 16.27m for 2,862 points.

Ukraine's Oleksiy Kasyanov moved up to second with 2,717 points, swapping positions with American Trey Hardee, who has 2,657 points heading into the day's remaining events, the high jump and 400m.

Early casualties included former world champion Tom Pappas of the US and Dmitriy Karpov of Kazakhstan, a bronze medallist from the 2003 worlds and 2004 Olympics.