IAAF president Lord Coe will double the world governing body's anti-doping budget as part of his plan to rebuild trust in athletics.
Since Coe was elected, Russia has been barred from world athletics for alleged involvement in widespread doping.
Coe said: "Be under no illusion about how seriously I take these issues."
The 59-year-old Briton, a former Olympic 1500m champion, was elected president of the IAAF in August.
He said: "I am president of an international federation which is under serious investigations and I represent a sport under intense scrutiny."
As well as taking the IAAF's anti-doping budget to £5.45m, Coe wants to appoint a new chief executive by the middle of 2016, establish a separate integrity unit for athletics before this summer's Olympics, and double the international testing pool of athletes to 1,000.
The integrity unit, one of Coe's election manifesto promises, will review issues such as doping, corruption, betting and age manipulation.
"My vision is to have a sport that attracts more young people," said Coe. "The average age of those watching track and field is 55. This is not sustainable."
He said the key was to create "a sport that people trust once more".
Coe added: "Athletics must be a sport that athletes, fans, sponsors, media and parents alike know is safe to compete in on a level playing field and one in which clean effort is rewarded and celebrated."
Diack is being investigated over allegations he took payments for deferring sanctions against Russian drugs cheats.
Davies, IAAF deputy general secretary, stepped aside while the organisation's ethics board looks into a plan to delay naming Russian drug cheats before the 2013 World Championships in Moscow. He denies wrongdoing.