The World Anti-Doping Agency says Russia helped hundreds of its athletes avoid checks. A report published on Wednesday puts further pressure on Russia, whose track-and-field athletes could be banned from the Olympics.
The report came just two days before the International Association of Athletics Federations (IAAF) convenes in Vienna to decide whether Russian athletes should be allowed to participate in the Rio de Janeiro Olympics.
A WADA summary said more than 736 tests between February 15 and May 29 of this year were declined or cancelled for a variety of reasons ranging from sample collection or athlete whereabouts.
Testers reported receiving hostile treatment when attempting to carry out drug tests. And the report contained anecdotal evidence of athletes flouting the tests. For instance, one track and field athlete was allegedly caught trying to provide a urine sample using a container inserted into her body.
"When she tried to use the container it leaked onto the floor and not into the collection vessel," the report read.
Russian athletics authorities have promised to try to clean up Russian athletics in an effort to avoid being banned from the 2016 Summer Olympics in Rio de Janiero.