Athletics: IAAF 'concerned' over Russian doping cases
Athletics governing body the IAAF says it is concerned about the number of Russian doping cases in the sport.
Out of 37 athletes sanctioned under the IAAF's biological passport programme since 2009, 23 are Russian.
On Tuesday, Russia's anti-doping agency banned five racewalkers, including three Olympic champions.
"The number of Russian doping cases in athletics generally, and in race walking specifically, is a major concern," said a statement.
London 2012 men's walk winner Sergey Kirdyapkin, women's 2008 Olympic gold medallist Olga Kaniskina and 2011 world champion Sergei Bakulin were all banned for three years and two months with their cases backdated from late 2012.
Olympic 2008 winner Valery Borchin was banned for eight years and Vladimir Kanaykin for life.
The IAAF also says that major international titles will be redistributed, although the bans do not affect any Olympic medals, but not until they have received and analysed the decision from the Russian Athletics Federation to make sure they are in compliance with their rules.
Separately, the World Anti-Doping Agency is investigating allegations of widespread doping and corruption in the sport after claims aired in a recent German television documentary, with a report due by the end of the year.