By Karolos Grohmann

LAUSANNE, Switzerland (Reuters) - Individual Russian track and field athletes assessed as clean will be able to compete for their country in Brazil, the Olympic Games' top official said on Tuesday, diluting a blanket ban the sport's global federation had called for.

International Olympic Committee President Thomas Bach also said all competitors from both Russia and Kenya would, given their countries' recent history of doping, have to be screened individually before being allowed to participate in the Games.

He did not elaborate on what the evaluation would include.

The Russian track and field team remains suspended from Rio de Janeiro after the IOC supported the ban, for systemic doping, which world athletics federation IAAF had extended on Friday.

But Bach, speaking at the end of a summit on doping, offered a limited number of Russian athletes the chance to race under their flag.

In a decision welcomed by the sports ministry in Moscow, he said those cleared by the IAAF or the Court of Arbitration for Sport as clean and eligible would be able to compete in Brazil.

The unsatisfactory record of anti-doping bodies in Russia, as well as Kenya, had put "very serious doubts on the presumption of innocence" of their athletes, Bach said.

But they had the right of appeal and "if there are (Russian) athletes qualified then they will compete as members of the Russian Olympic Committee team," he told reporters.

The IAAF had said on Friday that any Russian athlete would have to compete under a neutral flag, a recommendation it reiterated on Tuesday following Bach's comments.

"This decision has been unequivocally supported across sport and the IOC Summit today unanimously agreed to fully respect the IAAF decision," the federation said in a statement.

'SWIFT ACTION'

The Russian sports ministry, which had criticised the IAAF ban, said its Olympians were "ready to go over and above all the normal anti-doping tests to show their commitment to clean and fair sport."

"We have long stated that individual athletes in Russia are willing to demonstrate their innocence and prove they are clean," it said.

In Nairobi, Kenyan officials said they would cooperate fully with the IOC's stipulation.

"If that is the requirement for us to go to Rio, we shall fully cooperate. We have always done our best in the fight against doping," said Jackson Tuwei, the president of Athletics Kenya.

The IOC also ordered international federations to swiftly ban athletes found positive in re-testing of samples from the 2008 and 2012 Olympics.

A total of 55 athletes had tested positive for performance-enhancing drugs in those re-tests in recent weeks, none of whom would compete in Rio, the IOC said.

Bach also said the summit, including sports federations and national Olympic committees, had decided to review the anti-doping system, calling on the World Anti-Doping Agency to hold a global conference next year.

The IOC President said they had not discussed the potential participation in Rio of whistleblower Yulia Stepanova, a former drugs cheat whose revelations sparked the scandal, after the IAAF gave her hope of competing at the Games.

(Editing by Richard Balmforth and John Stonestreet)