Celebrated Latin American author and Nobel laureate Gabriel Garcia Marquez is suffering from dementia, according to his younger brother.

Jaime Garcia Marquez said the celebrated author has been suffering from dementia for some time and that the symptoms seemed to accelerate after he received chemotherapy treatment for lymphatic cancer in 1999. He made the comments to El Universal newspaper in Mexico, where his 85-year-old elder brother has lived for several decades.

The younger Garcia Marquez acknowledged that in the past, other members of his family have suffered from dementia and that he himself is starting to become affected. Both brothers grew up in Colombia.

He also spoke about his brother's condition during a recent lecture to students in Cartagena, Colombia.

"He is doing well physically, but he has been suffering from dementia for a long time," he said, noting that the two speak nearly every day.

"He still has the humour, joy and enthusiasm that he has always had," Jaime Garcia Marquez told the students, adding that his brother has ceased writing.

Though rumours have circulated that the author, affectionately dubbed Gabo, struggled with memory issues, Jamie Garcia Marquez is the first family member to speak publicly about his condition.

However, Jaime Abello, director of the Gabriel GarcĂ­a Marquez New Journalism Foundation in Cartagena, disagreed with the assessment.

Abello, who said he last saw the writer in April, told the New York Times that the Nobel laureate has not been clinically diagnosed as having senile dementia and that his condition was open to interpretation.

"He is a man of 85 with the normal signs of his age."

Gabriel Garcia Marquez, who won the Nobel Prize in 1982, is best known for his magic realism epic One Hundred Years of Solitude.

Published in 1967, the family saga spans the 19th and 20th centuries, has sold more than 30 million copies around the globe and been translated into more than 30 languages.

His other noted titles include Love in the Time of Cholera, Chronicle of a Death Foretold and, most recently, 2004's Memories of My Melancholy Whores. In 2010, he released a compilation of his speeches entitled I Didn't Come Here to Make a Speech.