The IOC didn't reveal where the athletes came from or their names, but said 12 countries and six different sports were involved.
The ruling body said its executive board "agreed unanimously to initiate proceedings immediately, with the 12 (national Olympic committees) concerned informed in the coming days."
"All those athletes infringing from anti-doping rules will be banned from competing at the Olympic Games Rio 2016," it added.
Tuesday's revelation only thickens the black cloud surrounding drugs and the Olympics, much of it involving Russia -- whose track-and-field athletes were banned from competing from Rio this year
due to regular doping in the past.
The former head of its anti-doping laboratory, Grigory Rodchenkov, told the New York Times
this month that more than half-a-dozen Russian medal winners were doping at the 2014 Sochi Winter Olympics.
Rodchenkov claimed he obtained the tainted samples and then helped to mask the illegal drugs by mixing in liquor.
The IOC said Tuesday it plans to conduct retests from 250 athletes who participated at the London 2012 Games and who potentially could participate in Rio.
Further, any athletes set to be awarded medals because others have been disqualified face having their samples -- which the IOC keeps for 10 years -- retested.
"All these measures are a powerful strike against the cheats we do not allow to win," IOC president Thomas Bach said in the statement. "They show once again that dopers have no place to hide.
"The retests from Beijing and London and the measures we are taking following the worrying allegations against the laboratory in Sochi are another major step to protect the clean athletes irrespective of any sport or any nation.
"We keep samples for 10 years so that the cheats know that they can never rest.
"By stopping so many doped athletes from participating in Rio we are showing once more our determination to protect the integrity of the Olympic competitions, including the Rio anti-doping laboratory, so that the Olympic magic can unfold in Rio de Janeiro."
The IOC requested that the World Anti-Doping Agency begin an investigation into the allegations made by the New York Times, "that testing at the Sochi Laboratory was subverted."
"Based on this investigation, the IOC will take swift action," it said.