MEXICO CITY - Mexico is formally starting extradition proceedings against captured drug lord Joaquin 'El Chapo' Guzman, the government said late on Sunday, in the strongest sign yet it intends to send him to the United States.

Guzman, the infamous boss of the Sinaloa drug cartel and the world's most prominent drug trafficker, was arrested in northwestern Mexico on Friday after a months-long manhunt.

On Sunday, Interpol served two extradition warrants, the Mexican attorney general's office said, kick-starting the latest attempt to have Guzman face US justice for the hundreds of tonnes of cocaine, methamphetamine and heroin he has exported across the border.

Mexico regularly extradites leading traffickers but the government of President Enrique Pena Nieto resisted handing over Guzman after his Feb 2014 arrest as a point of national pride.

That position changed after he escaped from a maximum security prison in July - for the second time in his career - by slipping away through a mile-long tunnel that surfaced in his cell.

Guzman has been taken back to the same facility over the weekend but, to avoid a repeat of that humiliation, Mexico's government says it aims to hand Guzman over to US justice as soon as possible. His lawyers are trying to block extradition.

The US government wants Guzman, who is believed to be 58 years old, tried on charges ranging from money laundering to drug trafficking, kidnapping and murder.