The Athletics Integrity Unit (AIU) has announced the disqualification of 20 athletes, including 10 from Nigeria, ahead of the opening day of competition at the Tokyo Olympics.
The athletes were told on Thursday that they couldn't take part in track and field events in Tokyo because they didn't meet anti-doping testing requirements.
The AIU requires athletes from 'high risk' countries to be given three no-notice, out-of-competition tests in a 10-month period heading into a major event.
Countries are deemed 'high risk' if they have deficiencies in testing programs.
Seven of the Category A countries had at least one athlete banned, including Belarus, Bahrain, Ethiopia, Kenya, Morocco, Nigeria and Ukraine.
The Athletics Federation of Nigeria (AFN) has since admitted "lapses" on its part over the disqualifications for not complying with out-of-competition drug testing requirements.
The AFN, which has been plagued by an ugly power tussle for several years, said they would take responsibility for the lapses that led to the disqualification.
"The AFN bears responsibility for any lapses that may have occurred during the process and reassures Nigerians that our performances (at Tokyo Olympics) will not be negatively impacted," it said in a statement.
"All our athletes resident in Nigeria and who qualified for the Olympic Games completed the three mandatory tests.
"Most of our top athletes resident in the USA also completed their tests.
"However, a few athletes in the American collegiate system were tested, but those tests were deemed not to have complied with WADA (world anti-doping agency) sample collection and analysis standards."
Nigerian sprinter blasts athletics officials
The AFN said it had appointed a top official to head its medical and anti-doping commission.
Sprinter Blessing Okagbare, who will compete in the 100m and 200m in Tokyo, has been highly critical of the country’s sports officials.
"The sport system in Nigeria is so flawed and we athletes are always at the receiving end of the damages," she said.
"They were busy fighting over power, exercising their pride over Puma contract/kits forgetting their major responsibility – the athletes.
"It’s sad that this cycle keeps repeating itself and some people will come out to say I am arrogant for speaking my truth.
"It’s my career."
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