Athletics' governing body (IAAF) will carry out its largest-ever anti-doping programme at the World Championships in Osaka later this month.
The IAAF is aiming to boost its fight against drugs
Over 1,000 samples will be taken during the eight-day event, eclipsing the 885 tests conducted at the 2005 Worlds.
"We will not tell the athletes what tests we will conduct, nor when," said IAAF president Lamine Diack.
He said the measures would "highlight our ongoing and aggressive commitment to the war on doping".
Diack added: "We know that the overwhelming majority of our athletes compete fairly, so it is for their sake that we must do all we can to chase down and sanction those who attempt to cheat and lie through the use of doping practices.
"Anyone considering cheating should be aware we will use every available method to catch them and that should we choose to do so, we can store their samples for testing at a later date."
Since January the IAAF has collected more than 1,000 unannounced out-of-competition samples.