A Catholic university said the president of Mexico met the requirements for graduation with a law degree, while acknowledging parts of his 1991 thesis were plagiarised.

Universidad Panamericana in Mexico City issued a statement late on Sunday, saying the thesis submitted by then-student Enrique Pena Nieto - elected president in 2012 - conformed with the standards of the time.

"The thesis introduced original ideas" and used outside ideas with and without citations, the statement said. "The (current) general regulations of our institution are not applicable to former students."