A World Anti-Doping Agency (WADA) report on the anti-doping methods employed at the Rio Olympics has highlighted serious failings.

The World Anti-Doping Agency says many athletes who’d been targeted for testing simply could not be found.

It added that, on some days, up to 50 percent of tests were aborted.

Its 55-page Independent Observers report found that, of the 11,470 athletes, 4,125 had no record of any testing in 2016.

It also said:

-Nearly 100 samples were not matched to an athlete because of data entry errors.

-One missing sample was not located until two weeks after the Games.

-There was little or no in-competition blood testing in many high-risk sports and disciplines, including weightlifting.

-There was no out-of-competition testing conducted in football, which WADA found “surprising”.

Without the dedication of doping-control staff, WADA says the anti-doping program would have almost certainly collapsed.

As of August 8, only 4,795 athletes were providing whereabouts information in the anti-doping system.

WADA mentioned several “failings” surrounding inadequate support for the chaperones employed to notify athletes of testing.