TORONTO -- Canadian shot putter Dylan Armstrong may yet get that bronze medal he narrowly missed at the 2008 Beijing Olympics.
Andrei Mikhnevich of Belarus, who edged Armstrong for bronze, was one of six athletes caught for doping in re-tests of their samples from the 2005 world track and field championships in Helsinki.
Mikhnevich threw 21.05 metres at the Birds Nest in Beijing, while Armstrong, from Kamloops, B.C., threw 21.04.
Mikhnevich, the 2003 world champion, had already served a two-year suspension for a doping offence, so a positive test from 2005 should result in a lifetime ban.
The IAAF -- the world governing body for track and field -- announced Friday it was opening disciplinary procedures against the six.
Among the other five athletes whose re-tests were positive was Belarusian shot putter Nazdeya Ostapchuk, who had already been stripped of her London Olympic gold medal for doping. She won the shot put at the 2005 worlds and finished second in 2003, 2007 and 2011.
Ivan Tsikhan of Belarus and Olga Kuzenkova of Russia -- men's and women's hammer throw champions at the 2005 world championships -- both tested positive.
Tsikhan won the Olympic bronze medal in 2008, and originally finished second at the 2004 Athens Games before being stripped of his silver medal for doping. He also won gold at the 2003 and 2007 world championships. Kuzenkova won the Olympic gold medal in 2004.
The other two are Vadim Devyatovskiy of Belarus, who took second in the hammer at the 2005 worlds, and Tatyana Kotova of Russia, who was second in the long jump.
The IAAF did not say for what substances the athletes tested positive, nor what the punishments could be.
"The IAAF's message to cheaters is increasingly clear that, with constant advancements being made in doping detection, there is no place to hide," IAAF president Lamine Diack said in a statement. "The IAAF will continue to do everything in its power to ensure the credibility of competition, and where the rules have been broken, will systematically uncover the cheats."
Frozen samples from Helsinki were re-tested by the IAAF just within the eight-year statute of limitations for drug violations laid down by the World Anti-Doping Code.
The IAAF said it re-tested samples using "the most up-to-date analytical techniques."
-- With files from The Associated Press.