The World Anti-Doping Agency cut the doping ban on Russian Liliya Shobukhova by seven months on Monday, saying the marathon runner had provided "substantial assistance" and was eligible for a lighter sentence.
"This brings the total length of the athlete's ineligibility period to two years and seven months which ended on 23 August 2015," WADA said in a statement.
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Shobukhova, 37, has been stripped of her London and Chicago marathon wins after the International Association of Athletics Federations (IAAF) said all her results since 2009 had been annulled and her two-year doping ban extended by 14 months after the Court of Arbitration for Sport (CAS) ratified a settlement agreement.
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The athlete, who triumphed in Chicago in 2009, 2010 and 2011 and in London in 2010, was originally suspended after irregularities were detected in her biological passport.
Shobukhova featured in a German documentary in December 2014 that alleged systematic doping by Russian athletes.
"Ms Shobukhova approached WADA in May 2014 with a view to providing substantial assistance. She accepted from the outset that she had committed an anti-doping rule violation," the agency said.
"The information and documentation provided by Ms Shobukhova has been of substantial value in uncovering and investigating anti-doping rule violations committed by other individuals including athlete support personnel," added WADA without mentioning any names.
"WADA considered the information provided by Ms Shobukhova to be of significant value to clean sport. As such WADA has decided to exercise its authority by agreeing to the use of the substantial assistance provisions in the 2015 Code."
The IAAF, the ruling body of athletics, said the ban reduction was permitted under its rules.
"The assistance that can be provided by athletes and support personnel in uncovering anti-doping rule violations is vital for the IAAF," it added.
"The IAAF encourages all athletes and other persons who have information that may assist in protecting clean athletes to provide this information to the IAAF or WADA."
Athletics has recently been hit by more doping claims and hundreds of suspicious tests that were allegedly not followed up on.
Image: Russia's Liliya Shobukhova leads the Women's elite race (picture for representational purpose only)
Photograph: Jed Leicester/Getty Images