The Athletics Integrity Unit made this known in a statement on Wednesday.

The AIU revealed that a total number of 18 athletes were ruled ineligible to compete at the Tokyo Olympics, with Nigeria accounting for the majority, with 10 athletes.

The names of the athletes were not released in the statement.

A major requirement of Rule 15 is that “an athlete from a ‘Category A’ country must undergo at least three no-notice out-of-competition tests (urine and blood) conducted no less than 3 weeks apart in the 10 months leading up to a major event. Only then do they become eligible to represent their national team at the World Athletics Championships or the Olympic Games.”

The athletes were ruled ineligible due to failure to meet the minimum testing requirements under Rule 15 of the Anti-Doping Rules for ‘Category A’ federations.

‘Category A’ federations are those that are deemed to have the highest doping risk and considered as a threat to the overall integrity of the sport.

The British pair lost 4-6 7-6 (7Andy-2) 10-7 against Croatia’s Marin Cilic and Ivan Dodig in the quarter-finals.

Murray, 34, and Salisbury were playing their first event together

Murray, who won the singles at London 2012 and Rio 2016, pulled out of the individual event with a minor thigh strain to focus on the doubles.

“I declare open the Games of Tokyo,” Naruhito said during a three-hour ceremony attended by just a few hundred officials and dignitaries and several thousand athletes in the 68,000-capacity Olympic Stadium.

Guinean Minister of Sports Sanoussy Bantama Sow announced the pullout of five athletes of the country.

Sow said “Due to the resurgence of COVID-19 variants, the Government, concerned with preserving the health of Guinean athletes, has decided with regret to cancel Guinea’s participation in the Tokyo Olympics”

Wrestler Fatoumata Yarie Camara, judoka Mamadou Samba Bah, swimmers Fatoumata Lamarana Toure and Mamadou Tahirou Bah and sprinter Aissata Deen Conte were due to compete for the West African nation at the Olympics.

Guinea is not the first country to withdraw from the Games. North Korea had announced in April that it would not attend Tokyo 2020 due to the Covid-19 pandemic.