Mexican journalist Carmen Aristegui, who is locked in a dispute with her former network over a book she co-authored on a scandal involving the wife of Mexico's president. (Henry Romero/Reuters)

MEXICO CITY — As he signed into law new anti-corruption measures earlier this week, Mexican President Enrique Peña Nieto took the opportunity to apologize for one of the defining scandals of his tenure: the purchase by his wife of a $7 million mansion through a favored government contractor.

Peña Nieto acknowledged that the "White House" scandal, as it came to be known, had battered his government's credibility, even though he claimed his family had done nothing illegal.

"With all humility, I ask your forgiveness," he said. "I reiterate my sincere and profound apology for the offense and indignation I have caused you."

But while Peña Nieto apologized, the news network that aired the story remains locked in dispute with the reporter who broke it, the famous Mexican television journalist Carmen Aristegui.

In the aftermath of her bombshell story from November 2014, which badly embarrassed Peña Nieto's administration, the relationship between Aristegui and her employer, Noticias MVS, deteriorated sharply. Four months after the report, MVS fired Aristegui and other members of her team, which critics considered an act of revenge and an attempt to silence a powerful journalistic voice.

Now that Aristegui has contributed to a new book, "La Casa Blanca de Peña Nieto," that dispute has flared yet again. The president of MVS, Joaquin Vargas, has sued both Aristegui, who wrote the prologue, and the publisher, Penguin Random House Editorial Group, over his depiction in her introduction. (The book was written by Daniel Lizarraga, Rafael Cabrera, Irving Huerta and Sebastian Barragan, reporters who worked on the original story with Aristegui).

Vargas's suit demands that the book be taken off the shelves and destroyed, that Aristegui offer a public apology, and that any future copies do not include Aristegui's prologue, according to lawyers for Aristegui and the publisher, who spoke to reporters Thursday.

Aristegui described the lawsuit, filed in late May, as part of a sustained campaign of harassment and bullying stemming from her coverage, plus an attack on freedom of speech. If Vargas's suit alleging "moral damage" wins, then "no one is safe, not us, nor our colleagues in other parts of the country," she said.

Felipe Chao, vice president of institutional relations and communications at MVS, said that Joaquin Vargas found the prologue "offensive."

"The prologue has declarations that are offensive to his person, that make accusations that are baseless and without proof," he said.

Chao said Vargas was particularly upset by Aristegui's claim that Vargas, who had earlier defended her work, "finally succumbed" to pressure from the politically powerful, resulting in her firing. Chao said Vargas was not interested in money from the lawsuit.

"What the lawyers are asking for is that Carmen proves what she's claiming in the prologue, or that she retracts it publicly," he said.

A lawyer for the publisher, Quetzalli De la Concha, said the request to separate the prologue from the book was "absurd" as it has to do with the "destruction, mutilation and modification" of a book, which undermines freedom of expression and the rights of the author.

Aristegui's original story centered on a mansion in the luxurious Lomas de Chapultepec neighborhood, purchased by first lady Angelica Rivera on credit from an entity that was part of Grupo Higa, a company owned by Juan Armando Hinojosa Cantú, which had received millions of dollars in contracts from Peña Nieto when he was governor of the state of Mexico. The company had also won a contract, subsequently canceled, to build a high-speed train between Mexico City and Queretaro, about 120 miles northwest of the capital.

Rivera later returned the mansion, and a government investigation subsequently found no wrongdoing by Peña Nieto or his wife. But the scandal contributed to Peña Nieto's plummeting approval ratings and the sense that corruption was one of the central failings of his government.

That issue has dogged the ruling Institutional Revolutionary Party, which took a hit in state and local elections last month, as it gears up for the next presidential election in 2018. Peña Nieto signed new laws that would increase oversight of public officials, but critics said the measures did not go far enough.

Gabriela Martinez contributed to this report.