Wednesday 1 June 2016 22:18, UK
The International Olympic Committee will target Russia, Mexico and Kenya in pre-Olympic drugs testing ahead of the Rio Games.
Olympic medallists from the Beijing 2008 and London 2012 Olympic Games will also be targeted in extended re-analysis of drug test samples, the IOC announced on Wednesday.
Thirty-one athletes tested positive following re-analysis of samples from the 2008 Games - as did a further 23 from London 2012 - and the IOC will now take further measures in its battle against doping, with particular scrutiny placed on athletes from Russia, Kenya and Mexico, where the testing programmes are "non-compliant".
"Special focus will be put on countries where the testing programme is non-compliant - Kenya, Russia and Mexico," the IOC said in a statement on its pre-Olympic testing programme after an executive board meeting on Wednesday.
An IOC statement added: "The re-analysis programme for the Olympic Games Beijing 2008 and London 2012 will be further extended.
"Together with WADA (the World Anti-Doping Agency), we will target medallists from both Olympic Games for possible re-analysis."
The announcements were made as part of the IOC executive board's five-point action plan to tackle doping ahead of the Rio Games, which open on August 5.
"The fight against doping is a top priority for the IOC, which has established a zero-tolerance policy," the statement added.
"The IOC will not hesitate to punish anyone within its reach responsible for using or providing doping products or methods, including officials, coaches and other members of the athlete's entourage."
The Olympic fate of Russia's track and field athletes - suspended by the IAAF, athletics' world governing body - is to be determined on June 17 after their suspension.
The IOC will then review the entire doping programme and measures being taken for Rio 2016 in October and lead the drive for independence.
It added: "The IOC will continue to push for all testing independent from sports organisations and to harmonise national and international testing under the leadership of a new entity.
"The IOC will lead by example and establish such an independent process, working with WADA, to be in place for the Olympic Winter Games PyeongChang 2018."
