Top five finishers plus two at random of each event were tested and 2,652 pre-competition tests were carried out between July 27 and August 8.

For the first time at a Games, athletes must provide whereabouts information for where they are residing, training and competing from July 27 to August 24. And an athlete can be tested twice a day.

Harsh punishments posed as a bigger deterrence to those who intend to cheat.

The IOC decided that as of July 1 this year, anyone banned for a doping offence for more than six months may not participate at the next summer or winter Games. The revised World Anti-Doping Code extended the ban for the first-time offender from two years to four years.

The IOC will keep all of the samples taken from Beijing for eight years and could retest them as more advanced testing techniques are developed.

Previously, the IOC stored samples that tested positive for 90 days and samples that tested negative for 30 days.

In the run-up to the Games, a bunch of offenders were stopped outside the Olympics which Rogge said was another reason for fewer cases  at the Games.

"We should not forget there have been 39 positive cases before the opening of the Village because we have worked with international federations and national Olympic committees, urging them to test as many as possible," said Rogge.

Seven top Russian female track and field athletes were accused of manipulating their urine samples and suspended from taking part in the Games.

Eleven Bulgarian weightlifters withdrew from the Games after positive tests and eleven members of the Greek national weightlifting team tested positive in March for the anabolic steroid methyltrienolone and banned for two years.