Algeria's Olympic 1500m champion Taoufik Makhloufi has become the latest big name to withdraw from the world athletics championships after failing to recover from a viral infection, the country's El Watan newspaper reported on Friday.

The 25-year-old had was taken ill in Ethiopia in January and has struggled since then, managing only an 11th-placed finish in a Diamond League mile race at Eugene in the United States on June 1 in a rare outing.

His manager Mohamed Azzoug told the El Watan website that Makhloufi had not recovered sufficiently to take part in the August 10-18 world championships in Moscow, although Algerian athletics officials said they had not been officially notified of his withdrawal.

Makhloufi was a controversial figure at the London Olympics, where he was disqualified from the Games by the IAAF for not making a "bona fide effort" after dropping out early in his 800m heat to preserve his energy for the 1,500 metres final, for which he had already qualified.

He then produced a doctor's certificate saying he had suffered an unspecific injury and he was duly re-instated and went on to take the 1,500 gold having improved his personal best over the distance by more than two seconds during the year.

Women's 1,500 metres champion, Asli Cakir Alptekin of Turkey, will also miss the world championships after failing a drugs test.

Leading sprinters Tyson Gay of the United States and Jamaica's Asafa Powell are also out after drugs test failures while world 100m champion Yohan Blake will not defend his title because of a hamstring strain.

Kenya's world and Olympic 800m champion David Rudisha is also absent with a knee injury.

Former world 800 metre champion Caster Semenya is likely to miss the worlds too after being left off South Africa's provisional list of 30 athletes released on Friday. 

Semenya, who won the world title in 2009 and ran second two years later, before grabbing the silver medal at the London Olympics, clocked a slow time in her first competitive race in over a year on Wednesday.

The 22-year-old would ordinarily be considered a good bet for a medal, but a knee injury that has plagued her since the Olympics and a pedestrian 800 metres win in a time of 2:06.58 in Finland have cast doubts over her readiness for Moscow.

Semenya would need to run 2:00.00 or quicker by July 29 to qualify for the championships, but her agent, Jukka Harkonen, told reporters earlier in the week that she had no more races lined up before the deadline.

Source: Agencies