New tougher anti-doping rules mean athletes must tell the authorities where they will be available for testing one hour each day.

Under current World Anti-Doping Agency guidelines, athletes list their whereabouts each day and can be tested at any time.

Normally, an anti-doping worker calls the athlete to set up the test but under the new system the athlete will not be contacted in advance for testing during the one-hour slot. If an athlete misses three tests then they are banned.

The new 60-minute window will enhance the no-advance-notice feature of the tests, which is considered the strongest part of the out-of-competition testing model. Athletes still will be subject to testing during any part of the day.

Erin Hannan, spokeswoman for the US Anti-Doping Agency said the revision "ensures harmonised, no-advance-notice testing around the world.

It incorporates into the standards the kind of best practices many of us are already primarily operating under.

"Without a phone call notifying them, it's a true no-advance-notice scenario."

A report issued this year by independent observers said 102 of 205 countries at the Beijing Olympics failed to tell organizers where their athletes were so they could be tested outside of competition.

It was one of the most glaring failures of the anti-doping system, according to the report.

Athletics has been hit by a string of high-profile drug cases in recent years.

One of the biggest cases saw American sprinter Marion Jones stripped of the five golds she won at the 2000 Olympics in Sydney, having admitted last-year she took performance-enhancing substances.