Isaac Izuu Makwala of Botswana in action at the 2012 African Athletics Championships in Porto-Novo, Benin Republic / Photo credit: Yomi Omogbeja

The International Association of Athletics Federations (IAAF) has defended the decision of its Medical Delegate to withdraw Botswana's star athlete Isaac Makwala from the Ongoing IAAF World Championships in London.

Makwala, was first prevented from competing in the men's 200m Heats on Monday night on the instruction of the IAAF medical staff after falling ill and vomiting.

The 30-year-old was then stopped by security guards at the London stadium entrance, and barred from Tuesday nights' men's 400m final in which he was a contender for a medal.

The IAAF said it was under instruction to quarantine athletes who showed symptoms of the "very virulent" norovirus - which broke out in the official hotel at the weekend.

The Athletics' governing body released a statement last night to defend its position:

Isaac Makwala (BOT) has been withdrawn by the IAAF Medical Delegate – click here – from tonight’s 400m final after the athlete was diagnosed with an infectious disease on Monday.

As per UK health regulations, it was requested that he be quarantined in his room for 48 hours, a period which ends at 14:00hrs tomorrow (9 Aug).

These procedures are recommended by Public Health England and were clearly explained to the teams in writing – click here – on Sunday (6 Aug) and in person to the Botswanan delegation, a member of which was present with many other representatives of teams at a meeting that took place at the Guoman Tower Hotel on Sunday.

The decision to withdraw him from the 200m heats last night and the 400m final today was made on the basis of a medical examination conducted in the warm-up medical centre by a qualified doctor on Monday (7 Aug) and recorded in the electronic medical record system of the championships. A copy of this medical record was given to a member of the BOT team medical staff following the examination.

The team doctor, team leader and team physio had been informed following the medical examination that the athlete should be quarantined for 48 hours and would therefore be missing the 400m final on Tuesday.

The IAAF is very sorry that the hard work and talent of Isaac Makwala won’t be on display tonight but we have to think of the welfare of all athletes.