A witness in the trial of Mexican kingpin Joaquin "El Chapo" Guzman says the drug lord bribed Mexico's previous president with a massive sum.

One of Guzman's lawyers first mentioned the allegation in his opening statement, naming two previous Mexican presidents.

The trial has been filled with accusations of bribery, but both presidents have denied the allegations.

A Colombian drug trafficker described as Joaquin "El Chapo" Guzman's right-hand man who spent several years hiding in northwest Mexico with him says the accused Sinaloa cartel chief paid a former Mexican president a $100 million bribe.

Hildebrando Alexander Cifuentes-Villa, known as Alex Cifuentes, said during testimony on Tuesday that Guzman paid $100 million to President Enrique Peña Nieto, who was in office from December 2012 to December 2018.

"Mr. Guzman paid a bribe of $100 million to President Peña Nieto?" Jeffrey Lichtman, one of the lawyers representing Guzman, asked Cifuentes during cross-examination, according to The New York Times.

"Yes," Cifuentes responded, adding that the bribe was conveyed to Peña Nieto through an intermediary.

Joaquin "El Chapo" Guzman arrives at Long Island MacArthur airport in New York after his extradition from Mexico, January 19, 2017. Thomson Reuters

Guzman's trial, now in its third month in the Eastern District of New York, has been replete with accusations of bribery, with witnesses describing millions of dollars a month in payments to law-enforcement and political figures.

Cifuentes' accusation is not the first of its kind leveled during the trial. During the defense's opening statement in November, Lichtman said that "hundreds of millions of dollars" in payoffs had been made "up to the very top," including Peña Nieto and his predecessor, Felipe Calderon.

Read more: 4 big takeaways from Sinaloa cartel chief 'El Chapo' Guzman's secretive US trial

The defense has sought to portray Guzman as a mere cartel functionary and Ismael "El Mayo" Zambada, who is considered Guzman's peer within the cartel and has never been caught, as the true power at the top of the Sinaloa cartel. (The Sinaloa cartel is believed to be more like an alliance of factions, rather than a hierarchical organization.)

Peña Nieto and Calderon both denied the Lichtman's accusation at the time. Calderon called them "absolutely false and reckless," and Peña Nieto's spokesman called them "completely false and defamatory," citing his government's pursuit, capture, and extradition of Guzman.

Joaquin "El Chapo" Guzman, center, sits next to his defense attorney Eduardo Balarezo, left, for opening statements in a courtroom sketch as his trial in the Brooklyn, New York, November 13, 2018. Elizabeth Williams via AP

At the end of the first week of the trial, Guzman's lawyers told the judge that Jesus Zambada Garcia, brother of "El Mayo," would testify that two Mexican presidents had been paid bribes. The judge, Brian Cogan, prohibited that line of questioning, saying it would cause unnamed "individuals and entities" embarrassment.

Zambada Garcia did testify that Mexico's former public-security secretary, Genaro Garcia Luna, had taken bribes, telling the court that he met Garcia Luna in a restaurant twice, giving him $3 million to $5 million in cash.

Read more: More Mexican leaders are being implicated in the Sinaloa cartel's dirty dealings during 'El Chapo' Guzman's trial

Garcia Luna also denied the accusation, calling it a "lie, defamation and perjury."

Alex Cifuentes, part of a Colombian family of drug traffickers that worked closely with Guzman's Sinaloa cartel, also said he'd been deeply involved with Guzman's operations, making deals for cocaine in Colombia and Panama, selling meth in Canada, moving drug proceeds across borders, and buying weapons.

An organizational chart of the Cifuentes Villa clan compiled by the US Treasury Department. US Treasury Department

Cifuentes said Guzman called him his "right-hand" and "left-hand" man. The two lived together at several hideouts in the mountains of northwest Mexico between 2007 and 2013, avoiding the Mexican army. Cifuentes was caught in 2013.

According to Cifuentes, Guzman was interested in making a movie about himself as early as 2007, long before he met actor Sean Penn at a mountain hideout — a meeting arranged by Kate del Castillo, a Mexican actress and one of Guzman's paramours.

Cifuentes said Guzman's wife first told him to film a biopic around that time and that Guzman hired a Colombian producer and planned a book to go along with the project, adding that the project got as far as showing a draft to Guzman's lawyers.