Bach said the Russia scandal along with Brazil's political and economic crises had made the runup to the first Olympics in South America "challenging". An investigation by Canadian lawyer Richard McLaren which revealed state-organised doping in Russia has overshadowed the buildup to the Rio Games which start Friday.

Eighteen canoeists and rowers made late appeals on Monday adding to challenges from three swimmers, a wrestler and the Russian weightlifting federation already in a queue at the Court of Arbitration for Sport (CAS).

But speaking at the opening session of an International Olympic Committee meeting, Bach said: "The findings in the McLaren report are very serious, in particular with regards to a system of doping allegedly orchestrated by the Russian ministry of sport.

"If proven true, such a contemptuous system of doping is an unprecedented attack on the integrity of sport and on the Olympic Games."

The IOC has been criticised for not ordering a blanket ban against Russia. But the German leader of the Olympic movement said there had to be "justice" for athletes who are clean.

"You cannot punish a human being for the failures of his or her government if he or she is not implicated," he said. Russia has denied any government backing for doping but its sports minister Vitaly Mutko has been barred from attending the Rio Games.

The IOC has ordered individual federations which organise the sports contest at the Olympics to filter out Russian athletes who should be banned over the doping. This has led to the wave of cases at the CAS which has organised special hearings in Rio to deal with the appeals.

About 30 Russians have now appealed, directly or indirectly, against bans from the Rio Olympics ordered by international federations. More could follow. CAS said in a statement that canoeist Andrey Kraytor and 17 Russian rowers led by Daniil Andrienko had also made appeals to the tribunal.

The first hearing for the rowers was scheduled for Tuesday when the tribunal would also decide whether more evidence would be needed in the case of Olympic medal winning swimmers Vladimir Morozov and Nikita Lobintsev.

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