A Frenchwoman who claimed to be a record 122 years old when she died was most likely a fraud and died at the age of 99, a controversial report has claimed.

Jeanne Calment is still on record as being the world's longest-living person when she died at 122 years and 164 days in 1997.

But Russian mathematician Nikolai Zak has cast doubt on that claim after examining biographies, interviews, photos and records of Calment.

In a report of his findings, Zak says the real Jeanne Calment most likely died in 1934, at age 58, and her daughter, Yvonne, acquired her mother's identity to possibly avoid paying inheritance tax. If true, that would make Yvonne 99 years old at her death.

Zak cites inconsistencies in Calment's interviews and discrepancies between her physical appearance and the likely appearance of someone her age.

Read more: World's oldest man dies in Japan at 112

'Defamatory' report

But some researchers have sharply criticized the claim.

French demographer Jean-Marie Robine, who helped authenticate Calment's age for Guinness World Records, told France's AFP news agency that Zak's report appeared to be "defamatory" against Calment's family and failed to examine evidence in favor of her longevity.

Toward the end of her life, Calment joked that God had forgotten about her and said she ate chocolate, drank port and smoked before her health began to deteriorate.

American Sarah Knauss, who died in 1999 at the age of 119, would receive the longevity record if Zak's claim is verified.

Read more: Genes and longevity - in humans and hydra

Despite Calment's alleged fraud, Zak said her life was an example for others to follow.

"She was a good example of healthy aging," he said.

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