Berlin  - Caster Semenya of South Africa won the 800 metres world title on Wednesday amid confirmation that a gender test was conducted on her to make sure that she was really a woman.

Semenya, 18, ran away from her rivals at the end of the final back straight to win in a world leading 1 minute 55.45 seconds.

Defending champion Janeth Jepkosgei of Kenya came second in 1:47.90 and Jennifer Meadows of Britain was third in 1:57.93 minutes.

The IAAF said the federation was conducting a double gender verification test on Semenya, who burst onto the scene a few weeks ago and on Wednesday raised her time by eight seconds compared to last year, in South Africa and in Berlin.

"At the moment there is no proof. The benefit of the doubt has to be with the athlete," said general secretary Pierre Weiss. "But if at the end it is proven (that she is not a woman) then the medal will be withdrawn."

Semenya was shielded from the media while Jepkosgei and Meadows did not want to comment properly. But Jepkosgei said "We competed, she beat us, everyone is surprised by her."

In other action, Brigitte Foster-Hylton stormed to 100 metres hurdles gold and mighty Usain coasted into the 200m final on a delightful evening for Jamaica.

Robert Harting sent a home crowd into ecstasy when he stole discus gold on his last attempt.

Kenya-born Yusuf Saad Kamel of Bahrain won the 1,500 metres gold in the doping-related absence of compatriot Olympic champion Rashid Ramzi, emulating his father Billy Konchellah who won the race for Kenya in 1987 and 1991.

Foster-Hylton saved the best for the final as she scored a season best 12.51 seconds for victory. She claimed her first major title, completing her set of medals at the worlds after silver in 2003 and bronze in 2005.

Olympic bronze medallist Priscilla Lopes-Schliep of Canada came second in 12.54 and bronze went to Jamaica again, with Delloreen Ennis London on 12.55 seconds. Olympic champion Dawn Harper of the US was no factor in seventh place with 12.81.

Harting, who has caused plenty of controversy with statements on doping, ripped his shirt to threads and shouldered the mascot after getting gold with a personal best 69.43m on his last attempt in his home town.

Malachowski, who had led from round one despite throwing with a fractured index finger, had to to settle for silver like at the Olympics with 69.15m while defending and Olympic champion Gerd Kanter of Estonia came third with 66.88m.

The Kenya-born Kamel outlasted world indoor champion Deresse Mekonnen of Ethiopia on the home stretch, crossing the line in 3 minutes 35.93 seconds.

"Nobody expected me to win. My father has two golds, now I want three to beat him," said Kamel.

Mekkonen had 3:36.01 and defending champion Bernard Lagat, a Kenya-born American, came third in 3:36.20. Lagat completed his set of 1,500m medals as he won a silver in 2001.

Bolt wasted little energy as he moved within one victory of a sprint double after three Olympic golds last year in 20.08 seconds, the final set for Thursday night little more than two hours ahead of his 23rd birthday.

"My birthday is on Friday, but I did not plan a party. As far as the 200m are concerned and a new world record? I have really not done the same amount of work like I did for the 100m," said Bolt.

Bolt won the 100m on Sunday in a stunning record of 9.58 seconds and is expected to attack his 200m mark of 19.30.

American Wallace Spearmon won the second semi-final in 20.14 seconds and compatriots Charles Clark and Shawn Crawford also made the final.

While Bolt is not expected to be beaten in the 200m, the US team hopes to turn the tide on the Jamaicans in the women's 200m.

Marsheyet Hooker led the heats with 22.51 seconds and two-time defending champion Allyson Felix also advanced with 22.88 seconds. Jamaican Olympic champion Veronica Campbell-Brown won her heat in 23.01 seconds.

In the 400m semis, the Olympic champion Merritt clocked 44.37 seconds in his semi-finals as he advanced along with fellow-American two-time defending world champion Jeremy Wariner, who won his race in 44.69 seconds.

Earlier in the day, three-time world champion Franka Dietzsch of Germany failed to make the discus final in her 10th appearance at the world while Ethiopian distance running star Tirunseh Dibaba did not compete in the 5,000m heats due to injury.

In addition, Cuban Olympic champion Dayron Robles stated a thigh injury which made him unsure whether he could continue in the 110m beyond the heats through which he barely advanced.

But Robles also said: "I promised Fidel Castro to bring home the gold medal for him. And I want to keep my promise."

Oleksey Kasyanov of Ukraine held an overnight decathlon lead with 4,555 points from Yunior Diaz of Cuba (4,512) and US athlete Trey Hardee (4,511).

Thursday's medal events apart from the men's 200m and completion of the decathlon are the 110m hurdles as well as the women's high jump and 400m hurdles. (dpa)