The World Anti-Doping Agency (WADA) passed a new code against the use of banned performance-enhancers Friday at the close of the World Conference on Doping in Sport in Johannesburg, South Africa.

World sport leaders revised the code, doubling the duration of the ban for those found guilty of doping to four years - effectively excluding cheats from the next Olympic Games. The new rule comes into effect at the start of the 2015.

"We are now equipped to go forward in the best possible way with a set of rules. It's a good day for sport, for athletes and for our future," said outgoing WADA president John Fahey.

"I firmly believe that the revised code will put the interest of clean athletes as the number one priority," Fahey said.

Attending the three days of deliberations were some 1,000 delegates.

Long deliberations

The finalization of the new code brings an end to a two-year process involving about 4,000 suggested changes to the last code, adopted five years ago.

WADA's statute of limitations will be extended from eight to 10 years, which will allow anti-doping agencies to store and test samples for up to a decade.

The changes come as the sporting world is reeling from several high-profile doping scandals including fallen Tour de France champion Lance Armstrong's doping confession.

Armstrong was stripped of his seven Tour de France titles after using banned blood-boosting drug EPO.

'Too many' loopholes

The code has, however, been met with some criticism. The International Association of Athletics Federations (IAAF) said the new rules did not go far enough and that they leave athletes "too many means of escape."

The four-year bans can be reduced to two if the doper denies the intention to have used a banned substance and they don't even have to prove it.

Admitting to cheating can also reduce the sentence, or if someone else takes the blame such as the athlete's support personnel.

All this will "make cases more procedurally complicated, time-consuming and costly than they ought to be," according to the IAAF.

Law in most countries

The third World Anti-Doping Code governs competitive sports from football to cycling, and has been backed by sporting bodies like the International Olympic Committee (IOC), world football's governing body FIFA, and governments.

More than 170 countries have ratified the UNESCO convention that contains the code, which means it becomes law in every country that ratifies it.

hc/ipj (Reuters, AFP)