The IAAF was acting on testimony from UK Athletics chief Ed Warner
The IAAF was acting on testimony from UK Athletics chief Ed Warner that the world body's then vice-president, and now president Sebastian Coe had told him Qatari delegates were handing out cash-stuffed "brown envelopes" before members cast their votes in 2011.
But the body's ethics board said Coe, when questioned, couldn't remember hearing the rumour or making the comment, and that nobody present had corroborated Warner's claim.
"To date, none of the respondents have had any relevant evidence corroborative of Mr. Warner's recollection or relevant to the alleged factual matters the subject of the purported rumour," a statement said.
London won the vote to host the 2017 world championships, while Qatar will hold the following edition in 2019 after coming out on top in a ballot in 2014.
Qatar was also embroiled in corruption allegations surrounding its successful bid to host the football World Cup in 2022.
A World Anti-Doping Agency report in January claimed that "corruption was embedded" in the IAAF, whose former president Lamine Diack has been charged with corruption, money-laundering and conspiracy.