By Karolos Grohmann and Jack Stubbs

RIO DE JANEIRO (Reuters) - Russian track and field suffered a final humiliation at the Rio Games on Saturday when the sport's governing body suspended long jumper Darya Klishina, removing from competition the nation's only athlete to have so far survived a blanket ban for doping.

The suspension, announced three days before she was due to compete, relates to new evidence uncovered by an anti-doping probe into allegations Russia ran a systematic, state-backed cheating program, said a source familiar with the matter.

Klishina defended herself, saying she was clean and was appealing against the decision to sport's highest tribunal. The Court of Arbitration for Sport (CAS) said it expected to rule on it by Monday, the eve of women's long jump qualifying round.

The 25-year-old had been given an exemption to compete in Rio while the rest of Russia's track and field team were banned from the Games by the International Association of Athletics Federations (IAAF) in response to the doping allegations.

Ahead of the Games, the IAAF had deemed that the U.S.-based athlete was not involved in the doping program and had been subject to sufficient drug tests outside Russia. But the source said new evidence emerged, prompting the IAAF to pull her exemption.

"We have withdrawn her exceptional eligibility status which enables her to compete in international competitions based on new information that has been received," an IAAF official told Reuters, saying the athlete had been notified last week.

Klishina reacted strongly in a Facebook posting, suggesting she was the victim of a political conspiracy - echoing comments by President Vladimir Putin who has said clean Russian athletes have been targeted by a shadowy plot emanating from the West.

"I am a clean athlete and have proved that already many times and beyond any doubt. Based in the U.S. for three years now, I have been almost exclusively tested outside of the anti-doping system in question," she wrote.

"I am falling victim to those who created a system of manipulating our beautiful sport and is guilty of using it for political purposes.

"I cannot help but feel betrayed by a system that is not focused on keeping the sport clean and supporting rank-and-file athletes, but rather seeking victories outside sport arenas."

Russian Olympic chief Alexander Zhukov backed her up: "The situation with Darya Klishina appears to be cynical mockery of the Russian sportswoman by the IAAF."

The IAAF did not explain its decision to suspend Klishina from the Games. But her mother, Nadezhda, was cited by Russian tabloid Komsomolskaya Pravda as saying investigators claimed to have found scratches on containers used to hold her daughter's samples from the World Championships in Moscow in 2013.

A World Anti-Doping Agency (WADA) probe, conducted by lawyer Richard McLaren, showed last month that Russian security officials had found a way to remove tamper-proof lids from test containers at the 2014 Sochi winter Olympics. This allowed them to swap dirty samples from Russian athletes for clean ones, but left incriminating scratch-like marks, the investigation found.

'I AM CYNICAL'

The IAAF barred the entire Russian athletics squad from the Rio Games even before McLaren released his interim findings last month, igniting world sport's biggest scandal in decades and threatening to split the Olympic movement.

Klishina was among 136 Russian athletes to appeal the ban and was the only one given the green light to compete in Rio.

The doping inquiry has cast a pall over the Games, fomenting what some have called an "anti-Russian atmosphere" in Rio and prompting the International Paralympic Committee to exclude Russia from its own Games next month.

Dmitry Shlyakhtin, head of the Russian Athletics Federation, said Russia had expected such a twist and that he thought it was unlikely the long jumper's appeal would be upheld.

"In general, I am cynical," he told Russia's R-Sport news agency.

(Editing by Mark Bendeich and Alison Williams)