The university where Mexican President Enrique Peña Nieto earned his law degree in 1991 acknowledged that he copied texts and ideas without crediting their authors in his thesis.
The PanAmerican University said Sunday that Peña Nieto's failure to properly credit texts included in his thesis did not violate the rules that were in force at the law school at the time.
The university's statement avoided the word "plagiarism," but did say the thesis included "textual reproductions of fragments (of other works) without footnotes or mentions in the bibliography."
It that he did attribute other quotes and material, although sometimes in a vague manner.
The university suggested that rules had become tighter, but noted "our university's general rules do not apply to ex-students" and said "this is an old case which cannot be subject to any action."
The news site Aristegui Noticias reported last week that 29 percent of Peña Nieto's thesis was material lifted from other works, including 20 paragraphs copied word-for-word from a book written by former President Miguel de la Madrid.
While the Mexican leader has not discussed the issue, a spokesman for Peña Nieto said last week that the president had completed all requirements for his law degree and downplayed the relevance of "style errors" in an academic work done 25 years earlier.
The thesis was titled "Mexican Presidentialism and Alvaro Obregón."
The news website is run by journalist Carmen Aristegui, who in 2014 broke the story that Peña Nieto's wife was purchasing a house with financing from a government contractor. The first lady eventually gave up the house and in recent months Peña Nieto has said he understands why the so-called "White House" scandal upset so many Mexicans.
A poll by the national newspaper, Reforma, this month found Peña Nieto's approval rating was at 23 percent, the lowest rating for any president since the paper began the survey in 1995. The margin of error was 3.3 percentage points.
It's not the first time that Peña Nieto's academic rigor has been called into question.
When he was a candidate for the presidency in 2011, Peña Nieto stumbled when asked to name three books that influenced him. He managed to mention the Bible, but then he fumbled through other mismatched authors and titles.
Based on reporting by the Associated Press.