Kiprop's failed test is measure of IAAF's willingness to catch even biggest names

Asbel Kiprop, the Olympic and three times world champion over 1500m, has tested positive for a banned substance.

His agent, Federico Rosa, would confirm only that he had 'heard the same rumour' and was 'still trying to get confirmation'.

But senior athletics sources have confirmed to Sportsmail that the man widely regarded as the finest 1500m runner of the last decade has failed an out of competition test.

Former Olympic and World Champion Asbel Kiprop tested positive for a banned substance

WHO IS ABSEL KIPROP? The Kenyan middle-distance runner specialises in the 1500m, winning Olympic gold in 2008 after Bahrain's Rashid Ramzi failed a drugs test. Aged just 19, Kiprop was the youngest Olympic 1500m champion since 1912. The 28-year-old is also a three-time world champion in the event — winning in 2011, 2013 and 2015 — but finished last in the 1500m final at London 2012. He came sixth at the 2016 Olympics and ninth at the World Championships in London. Advertisement

It is understood Kiprop is arguing there has been an error with a sample taken in late 2017.

On Wednesday night he said: 'I have read the reports linking me to doping. As an athlete, I have been at the forefront of the fight against doping in Kenya, a fight I strongly believe in and support.

'I would not want to ruin all what I have worked for since my first international race in 2007. I hope I can prove that I am a clean athlete in every way possible.'

It would represent a massive blow to athletics as well as Kenyan distance running when it was only last year that Jemima Sumgong, the Olympic women's marathon champion in Rio in 2016, tested positive for EPO and was banned for four years.

But it is a measure of the IAAF's willingness to catch even the biggest names since the formation of the Athletics Integrity Unit under the presidency of Lord Coe.

Kiprop has been on the start list of the opening Diamond League of the season in Doha since the event began in 2010 but he is not listed among the athletes to compete there this coming Friday.

The 28-year-old shot to prominence in 2008 when, aged just 19, he finished second in the Olympic 1500m final in Beijing. He was only narrowly beaten by Rashid Ramzi but his silver medal was upgraded to gold when the Bahraini runner tested positive for CERA, which is a modern form of EPO.

The positive test for Kiprop is a huge blow to both athletics and Kenyan distance running

Kiprop is widely regarded as the finest 1500m runner of the previous decade

At the world championships Kiprop dominated his event, winning in 2011, 2013 and 2015, running the third fastest 1500m in history in 2015 too.

A report in Kenya on Tuesday said a 'high profile runner' who has 'dominated world championships over the years' was embroiled in a doping scandal.

And they claimed that, while there was no confirmation from the Anti-Doping Agency of Kenya (Adak) or Athletics Kenya (AK), their sources has said the substance was the same blood-boosting drug used by Sumgong.

Once considered the home of distance running, Kenya have had a rash of positive tests – in 2016 they reported 40 cases over the previous four years - with marathon star Rita Jeptoo also being caught using EPO. Like Kiprop she too was managed by Rosa, who was the subject of a doping investigation by the Kenyan authorities in 2016.

Sources say the substance is the same as the one used by Jemima Sumgong (pictured)

The case was, however, dropped before it went to court and Rosa said he was fearful that Kiprop had indeed tested positive. 'I recognise it's a big story but if it's true it will be very sad,' he said.

A spokesperson for the AIU said: 'For confidentiality reasons, the AIU cannot confirm or deny a query of this kind.'

In a tweet on April 29, Kiprop said: 'Jesus had to died for your conveniency. But rose for your dreams. He died for us. He is alive & so we shall.'