Doping: Olympic champions among athletes banned by Russia
Russia's anti-doping agency has banned five athletes who compete in the walk, including three Olympic champions.
London 2012 men's winner Sergei Kirdyapkin, women's 2008 Olympic gold medallist Olga Kaniskina and 2011 world champion Sergei Bakulin have been banned for three years and two months.
Their cases have been backdated from late 2012.
Olympic 2008 winner Valery Borchin has been banned for eight years and Vladimir Kanaykin for life.
Kirdyapkin's ban will expire in time for him to be eligible to defend his title in Rio in 2016.
The bans do not affect any Olympic medals, although five world championship gold medals from 2009 and 2011 could be re-awarded.