Mexican authorities launched the process on Sunday to extradite drug lord Joaquin "El Chapo" Guzman to the United States, as they also sought to question US actor Sean Penn over their clandestine meeting.

The extradition bid marks a reversal from President Enrique Pena Nieto's refusal to send Guzman across the border before his July escape from a maximum-security prison.

The attorney general's office said in a statement that Interpol Mexico agents went to Guzman's prison near Mexico City to execute two arrest warrants for his extradition, two days after he was captured in a deadly military raid.

Mexico received the US extradition requests last year on a slew of charges, including drug trafficking and homicide. Guzman is wanted in a half-dozen US states.

A federal official said the process could take "months".

After judges rule on the extradition, the foreign ministry has to issue a decision, which Guzman can appeal.

His attorney has vowed a "tough" legal fight that could reach the Supreme Court.

Guzman is now back in the same prison that he escaped from on July 11 when he sneaked down a hole in his cell's shower that led to a 1.5-kilometer tunnel outside the prison.