(Reuters) - Ukrainian swimmer Olga Beresnyeva has tested positive for the banned blood booster EPO after her sample from the London 2012 Olympics was retested by the International Olympic Committee, it said on Friday.
"During further analyses conducted earlier this year on samples collected during London 2012, Beresnyeva, 29, was found to have tested positive for the presence of recombinant erythropoietin (rEPO)," the IOC said in a statement.
"These additional analyses were performed with improved analytical methods in order to detect prohibited substances which could not be identified with the analyses performed at the time (2012)."
The athlete had placed seventh in the 10km open water marathon.
The IOC keeps samples for several years after each Olympics in order to retest them using new methods or test them for performance-boosting substances that may have not been known at the time.
(Reporting by Karolos Grohmann in Baku; editing by Toby Davis)