South African Caster Semenya, dogged by gender accusations since shooting to fame in 2009, won a third world title in the women's 800m on Sunday.

Semenya, the defending Olympic champion and also world champion in 2009 and 2011, timed 1min 55.16sec, the fastest time of the year so far.

Burundi's Francine Niyonsaba, the Olympic silver medallist and world indoor champion, finished second in 1:55.92, with American Ajee Wilson taking bronze (1:56.65).

Wilson went out fast, with Niyonsaba on her coattails and Semenya happy to sit back in the pack. The South African was fifth going through the bell in a fast pace of 57.98sec.

Wilson made a move with 250 metres to run, Kenya's Olympic bronze medallist Margaret Wambui immediately falling off pace.

Hitting the home straight, Wilson and Niyonsaba were neck and neck before Semenya moved smoothly outside the lead duo and motored through the line for a convincing victory.

Semenya is back in the spotlight following a study funded by the IAAF and the World Anti-Doping Agency (WADA) that showed female athletes with naturally high levels of testosterone enjoy a competitive advantage of up to 4.5 percent over their rivals.

The 26-year-old South African was one of a number of women taking medication to lower her testosterone level until 2015 when the Court of Arbitration for Sport (CAS) suspended an IAAF rule that enforced a limit on naturally occurring levels.

Semenya has studiously avoided the controversy, instead concentrating on her track performances and she won a bronze in the highly competitive 1500m on Monday in the opening race of her ambitious bid for a distance double.

Semenya, who stands to be awarded the 2012 Olympic gold medal after Russian winner Mariya Savinova was disqualified for doping, now has to await further meetings between the IAAF and CAS to discover if she again has to take testosterone suppressing medication.