A view shows a plaque at the IAAF (The International Association of Athletics Federations) headquarters in Monaco November 4, 2015. [Photo/Agencies]

Diack is being investigated on charges that he asked for payment from Russian athletes to cover up positive dope tests.

"I had no knowledge in 2013 that IAAF officials might be involved in alleged criminal conduct in relation to doping cases, nor am I aware of any doping case that was not brought that should have been brought, or of any doping ban that was not published when it should have been published under the IAAF rules," Davies said.

"When information concerning alleged corruption was brought to my attention in early 2014, I was one of a number of IAAF staff members who referred the matter to the IAAF Ethics Commission and who have assisted in the resulting investigation by the Commission.

"I was also one of those staff members who voluntarily offered full assistance to investigators of the WADA Independent Commission as well as to the French and Monegasque Police Authorities and will continue to do so."