The world's oldest primary school student, Priscilla Sitieni, whose resolve to acquire an education in her 90s inspired a French film and won praise from UNESCO, has died in Kenya aged 99, local media reported.

Her grandson, Sammy Chepsiror, told The Standard newspaper that Gogo Priscilla (Granny Priscilla), as she was fondly known, died at home on Wednesday after developing a chest complication.

"Gogo has been in good health and attending her classes until three days to her demise when she developed chest pains, which forced her out of school," he told the newspaper on Thursday.

"We are thankful for the 100 years of her life. She made all of us proud," he added.

She was 94 when she persuaded the headmaster of the local school in her village in Kenya's Rift Valley to admit her, according to UNESCO, which hailed her as "a role model for her community and beyond".

In an interview with the UN agency last year, she said her aim was to motivate young mothers in Kenya to return to school after having children, instead of dropping out due to shame or fear of social stigma.

"I wanted to show an example not only to them but to other girls around the world who are not in school," she said.

"Without education, there will be no difference between you and a chicken," she said.

"Education is your future. Education remains in your head forever and you cannot lose it once you have it."

Her efforts were documented in a French film titled "Gogo", which led her to take a plane for the first time last year to visit France and meet first lady Brigitte Macron.

The film's co-writer Patrick Pessis paid tribute to her on Thursday, tweeting: "Her message about girls' education lives on."