Montreal - The World Anti-Doping Agency (WADA) said Tuesday it had retrieved 2 262 samples from Moscow's former drug-testing laboratory which will be subjected to further analysis.
WADA said in a statement investigators had collected A and B samples from the former laboratory which were split into 4 524 collection bottles.
The samples had been removed from Moscow for re-testing at a WADA-accredited laboratory outside of Russia.
"WADA Intelligence and Investigations is pleased to be continuing to make progress in this complex and difficult case," WADA investigations director Gunter Younger said.
"These samples will be used to strengthen cases against those who may have cheated and may exonerate athletes who have not committed an anti-doping rule violation."
The removal of the samples comes after WADA investigators retrieved a trove of analytical data from the lab in January.
Younger said the samples removed corresponded to data in the lab's database.
A progress report from the analysis of the information obtained from the laboratory would be sent to WADA's Compliance Review Committee in early May.
An update on the investigation would be presented to WADA's Executive Committee and Foundation Board meeting on May 15-16.
Providing full WADA access to the Moscow lab's data and samples was a key condition of Russia's controversial reinstatement last September following a major scandal over state-sponsored doping.
WADA wants to complete the review of data and samples by June 30 as part of the reinstatement deal, an agreement widely condemned by athletes and organizations worldwide.
The Russian Anti-Doping Agency (RUSADA) was suspended by WADA in November 2015 after revelations of a vast state-sponsored doping regime stretching back several years and spanning the 2012 Olympics, 2013 World Athletics Championships and 2014 Winter Olympics in Russia.