Joaquin "El Chapo" Guzman, Mexico's most infamous drug lord, has left his prison. Only this time he didn't escape.

Guzman, who has twice escaped federal prison in Mexico, was transferred from the Altiplano maximum-security prison outside Mexico City - the same prison he tunnelled out of last year - to a new lock-up in Ciudad Juarez, along the border with Texas.

Mexican authorities described the transfer as part of a regular shuffling of detainees to different facilities to help prevent escapes - some 7400 people have been moved around in a police implementation after Guzman's last break-out.

They also said in a statement that they were doing work to reinforce security in the Altiplano and Guzman's new prison, Cefereso No. 9.


But a former US Drug Enforcement Administration official, Mike Vigil, said he had been told by Mexican authorities that Guzman was moved because of fears about the security at Altiplano, considered the country's most impenetrable prison.

"He was moved strictly because of security concerns," said Vigil, a former chief of international operations who regularly follows the Mexican drug war.

"I know it's not going to be an internal threat, because they're watching him like a hawk. Because the [President Enrique] Peña Nieto Administration knows a third escape by Chapo Guzman would completely decimate the credibility of the Mexican Government."

Guzman's legal team has been aggressively opposing extradition to the United States, where he faces a variety of charges in several states for distributing cocaine, heroin and methamphetamine, among other crimes.

Little has seeped out about how Guzman has fared inside the Altiplano prison in the four months since he was recaptured in the Pacific coast town of Los Mochis, after trying to escape a military raid by fleeing through a sewer.

His new cell had better surveillance cameras - unlike the cell with the blind spot behind the shower wall that Guzman used to slip through a hole in the floor. His lawyers have told reporters that he had also been allowed fewer visitors.

Andres Granados, one of Guzman's lawyers, told the Mexican news outlet Milenio that his client had been moved without any prior notice to the legal team. This month, Guzman's visits had been suspended when the power went out in parts of the Altiplano prison where he had been held.

Vigil warned that the new prison in Ciudad Juarez was not as secure as Altiplano, and that Guzman's Sinaloa drug cartel controls that drug trafficking territory.

"The penitentiary is vulnerable," he said. "It's not the best penitentiary on the planet."

A Mexican security official denied there was a security threat at Altiplano or that the Government was preparing for Guzman's extradition, but did not elaborate on the reasons for the transfer.