In the latest scandal affecting Turkish track and field during Istanbul's bid to host the 2020 Olympics, 31 athletes have been suspended for two years each for doping violations.

The Turkish Athletics Federation announced the sanctions Monday, including that of hammer thrower Esref Apak, the 2004 Olympic silver medalist. His case had been announced in June.

The bans follow five days after the IAAF confirmed that nine Turkish athletes, including two teenagers, got two-year bans for using anabolic steroids.

It could get worse for the sport in Turkey when TAF completes investigations into alleged doping by Asli Cakir Alptekin, the women's 1,500-metre champion at the 2012 Olympics, and two other female team members in London last year.

"The files of Asli Cakir Alptekin, Nevin Yanit and Pinar Saka were not assessed because the process of investigation following their defense statements is continuing," the federation said Monday in a statement published on its website.

Turkey's doping problems threaten to affect Istanbul's campaign against 2020 Olympic bid rivals Madrid and Tokyo. International Olympic Committee members will choose a winner on Sept. 7.

Still, Turkey's most senior Olympic official said Monday's sanctions were "a clear signal" of how seriously it is responding.

"This work is part of a concerted, and much more aggressive, anti-doping policy in Turkey that has been in place for over six months," Turkish Olympic Committee president Ugur Erdener, an IOC member, said in a statement.

At least three of the 31 new suspensions, including Apak, were on Turkey's London Olympic team. Tugce Sahutoglu competed in women's hammer and Elif Yildirim was in the 4x400 meters relay squad.

The TAF listed all 31 athletes' names without specifying details of their doping violations or dates of their suspensions from competing.

They included another men's hammer thrower, Fatih Eryildirim, who competed alongside Apak at the 2011 world championships in Daegu, South Korea.

Many suspensions were expected after reports that multiple athletes tested positive in a targeted program before the Mediterranean Games, which Turkey hosted in June.

The stream of Turkish doping cases prompted TAF chairman Mehmet Terzi to resign last week after nine years in office.

"I look forward to working closely with the new incoming chairman of Turkish athletics who I will expect to aggressively seek out and expel all athletes who cheat using performance-enhancing drugs," Erdener said. "Led by the Turkish Government, Turkey has zero-tolerance for doping and it is our intention to have clean, young athletes competing on the international sporting stage in the future."

Fresh revelations in Turkey prompted FIFA to "reassess" more than 600 samples taken there in the past year.

FIFA said it was "concerned by the apparent widespread scope of the scandal" but found no soccer players had tested positive for banned drugs.