MEXICO CITY (Reuters) - Mexican President Enrique Pena Nieto plagiarised nearly a third of his 1991 undergraduate law thesis, according to a report published on Sunday (Aug 21) by one of Mexico's leading investigative journalists.

Of the 682 paragraphs that made up the 200-page thesis, titled "Mexican Presidentialism and Alvaro Obregon", 197, or 28.9 per cent, were found to be plagiarised, the report said.

The article and accompanying video were published on the website of journalist Carmen Aristegui, whose investigative team revealed in 2014 that Mr Pena Nieto's wife was in the process of acquiring a luxury home from a government contractor.

The Casa Blanca scandal, as it came to be known, dealt a major blow to the reputation of Pena Nieto, whose poll numbers have recently hit all-time lows over perceptions he and his Institutional Revolutionary Party (PRI) have failed to stamp out rampant crime and corruption.

In a statement, government spokesman Eduardo Sanchez sought to play down the accusation of plagiarism, instead calling the omissions "style errors".

He added that Mr Pena Nieto met all the requirements needed to graduate as a lawyer from Panamerican University.

In 2015, Ms Aristegui was dismissed by her employer, MVS Radio, after it accused her and her team of offering, without prior authorisation, the broadcaster's name and funding for a new platform for investigative journalism called Mexicoleaks.

Ms Aristegui argued her dismissal was politically motivated.