Amusan, the world champion in the 100m hurdles, had been charged with missing three doping tests within a 12-month period last month, leaving her participation at the World Championships in doubt. 

However, a Disciplinary Tribunal panel found by a majority decision Amusan had not committed an anti-doping rule violation. 

The reasoning for the decision is yet to be published, but the AIU through its head Brett Clothier has expressed its disappointment and plans to review the ruling before deciding whether to appeal to the Court of Arbitration for Sport. 

Competition in the 100m hurdles at the National Athletics Centre in Budapest is due to be held from Tuesday (August 22) to Thursday (August 24). 

Amusan protested her innocence after being charged by the AIU, insisting she is a "clean athlete" and "regularly" tested. 

She also said she had been tested "within days" of missing her third test.

Three whereabouts failures in a 12-month period can lead to a ban of between one and two years depending on an athlete's degree of fault.

Amusan expressed her elation at being cleared to compete.

"I am thrilled to put this behind me, and I look forward to defending my title at next week's World Championships," she wrote on Instagram.

"I generally have been and consistently will be an ally for clean sport."

Amusan had shaved 0.08sec off the 100m hurdles at last year’s World Championships in Eugene with her semi-final time of 12.12, and was one of 12 athletes who set personal bests in that stage of the event.

The now-26-year-old bettered that with a 12.06 effort in the final, but that was not ratified as a world record due to excessive tailwind. 

Amusan had faced claims her Adizero Avanti Tyo Tinman Elite shoes gave her an unfair advantage, but her semi-final performance was ratified as a world record by World Athletics in September last year. 

She is also a two-time Commonwealth Games champion, back-to-back African champion and Diamond League Final winner in the 100m hurdles.