A total of nine athletes, including Olympic bronze medalist Nataliya Tobias, have tested positive for "sophisticated doping" offenses, the International Association of Athletics Federations (IAAF) has confirmed.

Six of those athletes were caught using a new "biological passport" method, which builds up a profile of each individual over a prolonged period of time.

The remaining three, including Tobias who came third in the women's 1500 meters in Beijing four years ago, were suspended after further analysis of samples they gave at the World Championships in Daegu last year.

"Today's announcements underline the IAAF's continued and unwavering campaign against doping in athletics," IAAF President Lamine Diack said in a statement on their official website.

"They demonstrate the IAAF's commitment to use advanced methods to detect doping and to enforce increased sanctions when justified.

"We will not stint in our resolve to do everything in our power to eradicate cheating."