MEXICO CITY (Reuters) - Widely derided after a report that he plagiarized nearly a third of his university law thesis, President Enrique Pena Nieto conceded on Thursday that he may have made a "methodological error".

Speaking at an unscripted question-and-answer forum at his ceremonial palace in downtown Mexico City, Pena Nieto said he had not intended to steal anyone else´s ideas when he compiled his 1991 thesis about Mexico´s presidency.

When the story by one of Mexico's leading investigative journalists broke last month, Pena Nieto´s spokesman Eduardo Sanchez dismissed the reported plagiarism as "style errors".

"I can remember my studies well, remember how I researched, and what I put forward in my thesis. Nobody can tell me that I plagiarized my thesis," Pena Nieto said. "I may have misquoted or not quoted well one of the authors consulted - it may well be."

"I may have committed some methodological error," he added. "But in no way did I want to appropriate the ideas of others."

In late August, Mexican journalist Carmen Aristegui reported that 28.9 percent of the president's 200-page thesis, titled 'Mexican Presidentialism and Alvaro Obregon,' were found to be plagiarized.

The plagiarism report was one of a series of blows that Pena Nieto has been forced to fight off, after he, his wife and his finance minister were enveloped in a series of conflict of interest scandals.

(Reporting by Natalie Schachar and Jean Luis Arce; Editing by Simon Gardner)