Accreditations of laboratories in Beijing, Bloemfontein and Lisbon have all been removed in recent weeks.

WADA have not provide precise details as to why the three decisions were made, due to "ongoing legal processes that include the laboratory’s right of appeal to the Court of Arbitration for Sport".

A spate of "false negative" tests were to blame in the case of Beijing and may also have been significant with the other two.

A total of 31 WADA-accredited laboratories now remain in the world, but there are currently none in Africa.

"I am aware that these suspensions come at a time when the eyes of the sporting world are fixed on the Rio 2016 Olympic and Paralympic Games," said Sir Craig in a statement released by WADA this evening.

"Understandably, some athletes might question whether, in light of these suspensions, they can retain full confidence in anti-doping sample analysis procedures.

"It is important for athletes to note that, as a result of these suspensions, all samples will now be transported securely to one of the remaining 31 WADA-accredited laboratories worldwide, thereby ensuring that there are no gaps in the anti-doping sample analysis procedures and that the integrity of the samples is fully maintained.

"I wish to stress that the three laboratory suspensions are a direct result of WADA’s strengthened laboratory monitoring process."

It comes after a busy period for WADA in which they have received widespread criticism for their handling of the adding of meldonium to the banned substance list at the beginning of this year.

More than 100 athletes subsequently tested positive - including Russian tennis superstar Maria Sharapova - before WADA admitted that more research is required to ascertain how long the product stays in the human body.

A process is also continuing to inspect and make changes to the Russian anti-doping system following a declaration of non-compliance following allegations of state-sponsored doping there in athletics.

Sir Craig told insidethegames this week he intends to step down from the International Olympic Committee Executive Board later this year partly in order to focus upon his WADA work.

It is claimed that a more rigorous assessment process has led to the latest revoking of accreditations, along with more frequent site visits by independent experts and WADA personnel.

"I can assure you that WADA is committed to supporting all of its accredited laboratories in maintaining or reaching the Agency’s more stringent laboratory monitoring standards; and, with this, athletes can have full confidence that this, too, is a strong link of the anti-doping chain," Sir Craig said. 

"WADA will continue to work with the suspended laboratories to ensure that the necessary requirements are met."