International Olympic Committee (IOC) President Jacques Rogge said on Friday that a spate of failed drugs tests ahead of the London Games proved authorities were winning the war on doping.
Speaking ahead of the official opening of the Olympics, the IOC president said he welcomed the fact that cases involving around 15 athletes had been confirmed leading up the Games.
"As far as the athletes being caught before the Games, this is a good sign for the fight against doping," Rogge told a press conference.
"We are continuing to test, test and test again. This is proof that the system works, that the system is effective, and that the system is a deterrent."
A mammoth 71,649 tests have been carried out worldwide in the six months leading up July 19, with 107 athletes sanctioned, according to the World Anti-Doping Agency.
London organisers say more than 6,000 tests will be carried out during the Games itself, billing the Olympics as the most tested ever.
In the latest cases on Thursday, Turkish Weightlifting Federation (THF) president Hasan Akkus confirmed that weightlifters Fatih Baydar and Ibrahim Arat had been expelled after failing dope tests on July 7.
Zoltan Kovago meanwhile became the second Hungarian discus thrower to be kicked out of the Olympics after he refused to undergo a drugs test, following the expulsion of fellow discus thrower Robert Fazekas last week.
Greek world indoor high jump champion Dimitris Chondrokoukis was also confirmed to have failed a drugs test and was ruled out of the Olympics.
The latest cases followed an announcement by the International Association of Athletics Federations (IAAF) that nine athletes, including Olympic bronze medallist Nataliya Tobias, had been involved in "sophisticated doping".
Morocco's Mariem Alaoui Selsouli, one of the favourites for the women's 1500m gold medal, was also ruled out of the Olympics after failing failed a drugs test in Paris earlier this month.