The International Olympic Committee said Wednesday it would take up to a week to decide whether to ban Russia from the Rio Olympics over its "state" doping machine.

Amid widespread agonising within the IOC over how to handle its biggest doping scandal, the final verdict could come less than 10 days from the Rio opening ceremony on August 5.

The IOC executive decided on Tuesday to wait until after a Court of Arbitration in Sport (CAS) ruling expected Thursday before deciding whether a blanket Olympic ban on Russian competitors should be imposed.

The IOC, which said it needed to study all "legal options", has now signalled it will take every day possible for one of the most important decisions in Olympic history.

"We expect a decision within seven days on the participation of Russian competitors in Rio," IOC media relations chief Emmanuelle Moreau told AFP.

The IOC has already banned Russian Sports Minister Vitaly Mutko and all other ministry officials from the Rio Games and withdrawn backing for international events in Russia over the doping programme revealed by Canadian lawyer Richard McLaren this week.

McLaren, who produced a report for the World Anti-Doping Agency, said there was a "state-dictated failsafe system" of drug cheating. IOC president Thomas Bach called Russia's actions a "shocking and unprecedented attack on the integrity of sport and on the Olympic Games."

WADA has called for Russia to be banned and are believed to have backing from the United States, Canada, Germany, Japan and other nations.

"It's a complex issue to ban a country, but we're delighted to see they're considering it," New Zealand Olympic Committee secretary-general Kereyn Smith said.

But some senior officials have expressed doubts whether the IOC wants to expel Russia.

Dick Pound, an IOC member and former WADA president, said it was right for the IOC to take time to make a decision.

But he added: "I do get the impression reading between the lines, however, that the IOC is for some reason very reluctant to think about a total exclusion of the Russians."

Pound said an Olympic ban "would force Russia to acknowledge that the rest of the world is not prepared to play with them unless they change."

Several national Olympic committees have also voiced support for Russia's case that it would be wrong to exclude Russian athletes who have not failed drug tests.

Italian Olympic committee president Giovanni Malago said athletes were right to complain about Russian drug cheats.

But he said no one can say all Russian athletes are cheats and added: "In the public's imagination participation in the Olympics is for everyone. So I cannot imagine it without Russia."

The Association of Summer Olympic Federations has also urged caution.

The IOC said after Tuesday's executive talks it will "explore the legal options with regard to a collective ban of all Russian athletes" against "the right to individual justice."

Evan Bach has called for a way to let clean athletes compete in Rio.

It must first wait for the CAS ruling on an appeal by 68 Russian athletes against an Olympic ban ordered by the International Association of Athletics Federations.

The IAAF suspended all Russian track and field competitors after an earlier inquiry, chaired by Pound, found widespread "state-sponsored" doping in athletics.

While waiting for the legal opinions, the IOC has barred Mutko, a long-time ally of President Vladimir Putin, from the Rio Games.