Mexico's President Andres Manuel Lopez Obrador said Tuesday that the United States had been in talks with Joaquin Guzman Lopez, son of drug lord "El Chapo," ahead of his detention alongside a sought-after cartel boss last month.
Mystery has surrounded the detention of Guzman Lopez and the highly wanted co-founder of the Sinaloa Cartel Ismael "El Mayo" Zambada, who had both arrived on a private plane in Texas last month.
Various US media reports have suggested "El Mayo" was duped by Guzman Lopez into getting aboard, or was ambushed and forced to do so.
"What they (the Americans) told us was about Guzman Lopez, that they had talks with him and that suddenly not only Guzman Lopez arrived but Mr. Zambada arrived," the president told his regular press briefing.
Security Minister Rosa Icela Rodriguez previously said that US agents had received around two hours' notice that Zambada -- one of Mexico's most-wanted drug traffickers -- was on board the aircraft.
Both men were detained after disembarking at an airport near El Paso on July 25, but details of their capture remain murky.
US authorities have not officially confirmed any talks with Guzman Lopez ahead of the arrest, nor the existence of a deal under which he would turn Zambada over to US law enforcement.
Zambada's lawyer, Frank Perez, has maintained that his client was "kidnapped" and taken to the United States against his will.
The US State Department had offered a reward of $15 million for the arrest of Zambada and $5 million for the capture of Guzman Lopez.
Last week, Zambada, 76, appearing frail and in a wheelchair, was in a Texas court where he pleaded not guilty to charges of drug trafficking, money laundering and conspiracy to commit murder.
Guzman Lopez was transferred to Chicago, where he pleaded not guilty to drug trafficking charges.
The Mexican government has maintained it played no role in the men's capture.
Lopez Obrador declined to give more details, saying he was waiting for more "official information" from Washington in what was a "delicate matter" that could generate "a greater conflict" in Mexico.