91�ȱ�

Russia's athletics head coach Valentin Maslakov has resigned.

On Tuesday, Russia's anti-doping agency banned five race walkers.

Russian athletics president Valentin Balakhnichev said: "Even though Maslakov has nothing to do with anti-doping policies of the athletics team, he could not stand by idly and decided to take responsibility for those who he was in charge of."

Maslakov, 70, had overseen the training of Russian team athletes since 2007.

His entire coaching career has spanned more than 40 years.

Athletics' governing body the IAAF says it is concerned about the number of Russian doping cases in the sport.

A total of 23 of the 37 athletes sanctioned under the IAAF's biological passport programme since 2009 have been Russian.

London 2012 men's 50km walk winner Sergey Kirdyapkin, women's 2008 Olympic 20km gold medallist Olga Kaniskina and 2011 50km world champion Sergey 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.

Abnormal blood levels in the sportsmen's biological passports were the reasons for the bans.

The World Anti-Doping Agency is investigating allegations of widespread doping and corruption in the sport after claims were aired in a recent German television documentary, with a report due to be published by the end of the year.

Claims that a top British athlete escaped a doping inquiry after officials decided not to look into 150 suspicious blood samples were among the allegations broadcast.

That prompted a separate investigation by the IAAF, which had been accused of failing to take action.

An earlier programme shown by a German broadcaster alleged that as many as 99% of Russian athletes were guilty of doping.

Those claims were rejected as "lies" by the Russian Athletics Federation, which has also launched its own investigation.