An elderly Costa Rican man reportedly born at the turn of the 20th century could be the world's oldest at 115, but his lack of documentation and testimony from family and friends could see him out of the record books.

Jose Delgado, better known locally as "Chepito", is remarkably active for his purported age with the nuns at his nursing home reporting the alleged super-centenarian to be in good health. Despite his poor eyesight, he goes out for walks as well as exercises on the machines at his residence.

"He does exercise as part of an individualised therapy which is varied and alternates. There are times when he uses a treadmill for 15, 20 minutes, or on the bicycle for 15, 20 minutes. And other exercises focused on balance, reflexes, stimulation to maintain alertness to protect from any risk of falling," said his physiotherapist.

For Delgado's reported age to qualify for a world record he needs to be validated by an international organisation that deals with longevity research as well as arrange for an official from Guinness to come to Costa Rica to check his information.

Luis Bolanos, Director General at Costa Rica's Civil Registry said official records back up the oldest-man-in-the-world claim.

"Specifically speaking, Jose is 115 years, five months and one day old. He was born in March, 1900 in accordance with the original birth certificate. This certificate was declared on 12 March 1900 before a civil register," he said.

Never married and without children, Delgado is reportedly one of the healthiest patients at the home.

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