A report from the World Anti-Doping Agency (WADA) claims almost half of the planned doping tests at this summer's Rio Olympics were aborted on some days because athletes could not be found.
The 55-page WADA Independent Observers report accused the Rio 2016 anti-doping department of "a lack of coordination," which it said placed a massive strain on drug testing at competition venues and the Athletes Village.
"Chaperones were often provided with little or no whereabouts information for athletes targeted for out-of-competition testing in the Athletes Village, and therefore, the majority of times had to resort to asking team officials and/or athletes from the same team where the athletes they were looking for were located," the report read.
"Providing the names of the athletes they were seeking was (at best) highly inefficient and obviously compromised the 'no notice' nature of the testing.
"In addition, when initial attempts to find an athlete in his or her room were unsuccessful, chaperones often lacked the training and/or the confidence to follow up with further enquiries and effort to find the athlete in other locations in the Village (such as the dining hall).
"Ultimately, many athletes targeted for testing in the Athletes Village simply could not be found and the mission had to be aborted. On some days, up to 50 per cent of planned target tests were aborted in this way."
The report criticized the lack of support and unsatisfactory working conditions for chaperones, which led to many not turning up.
Poor transport arrangements and a failure to supply suitable computing facilities were other issues highlighted in the report.
It was also revealed that no out-of-competition testing was carried out in football, while high-risk sports like weightlifting had little or no in-competition blood testing.
The report also said that in the run-up to the Games over 4,000 athletes scheduled to compete in Brazil had no drug-testing record during 2016.
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Officials had been tasked with conducting 5,380 tests during the event, but only 4,882 were successfully completed.
Commission chair Jonathan Taylor conceded the anti-doping program had experienced some issues, but claimed a number of positive outcomes had been achieved.
"Despite staffing issues, resource constraints and other logistical difficulties, those tasked with implementation of the program, and in particular the volunteers, deserve immense credit for ensuring that the rights of clean athletes were safeguarded," Taylor said.
The report also praised improvements made to Rio's anti-doping laboratory, which had been suspended by WADA just over a month before the Games for failing to meet international standards.
However, Dr Richard Budgett, the IOC's medical and scientific director, has a slightly different opinion on the matter.
"The IO [Independent Observers] report shows that it was a successful Olympic Games with a successful anti-doping programme,” reads the statement on the IOC website, citing Dr Budgett.
"The integrity of the program was ensured despite some challenges the Organising Committee had to overcome.
"I would like to thank all the involved experts, staff and volunteers," said Budgett.
"The IO recommendations for future Olympic Games will be carefully studied and considered by the IOC and passed on to the new independent testing authority (ITA), which is planned to be in place before the next Olympic Winter Games PyeongChang 2018.
"The IOC looks forward to working with International Federations, National Anti-Doping Organizations and National Olympic Committees to ensure that organizers of future Olympic Games and the ITA deliver harmonized but sport-specific anti-doping programmes at future Olympic Games."