El Chapo will be tried in the US in April 2018

The hearing came the day after Cogan refused to order Guzman released from solitary confinement in a New York City federal prison, where his court-appointed lawyers have said he faces needlessly harsh and restrictive conditions that make it hard for him to mount his defense.

The 27-year-old mother of his twin daughters sat in the gallery, dressed head to toe in white.

But Cogan refused a request for amnesty global to visit on the grounds that there was "absolutely no reason".

Guzman's court-appointed lawyers argued in March that he was being held in unnecessarily harsh conditions and asked that he be released into the general prison population.

Judge Brian M Cogan ruled Guzman must remain in solitary confinement, can have limited visitors and a limited ability to communicate with the outside world.

"The conditions are reasonably necessary to ensure that defendant can not coordinate any escape from prison, direct any violence against cooperators, or manage any aspect of the Sinaloa Cartel's enterprise", he wrote.

He went on to write that Guzman's second jail break in Mexico "was accomplished under 24-hour video surveillance in solitary confinement".

He returns to court Friday. His wife is also expected to attend.

The messages, the judge said, can discuss the hiring and paying of lawyers or can be "of a personal nature". "That's true no matter who you are and what you are accused of", she said.

"We will continue to fight for his right to fair and humane treatment".

Michelle Gelernt, one of Guzman's lawyers, again brought up the conditions of Guzman's imprisonment at Friday's hearing, saying it was hard to review evidence because lawyers were only allowed to speak to Guzman through a plexiglass barrier.

The Mexican kingpin, who is due in court for a hearing Friday, is being held in the Special Housing Unit of Manhattan's Metropolitan Correctional Center, where he is confined to his cell up to 23 hours a day and has not been allowed to visit with anyone beyond his legal team.

The judge ordered USA prosecutors to "cease any communications with MCC staff" in which prison employees report back on the content of those meetings.

In March, the defense complained Guzman's health was deteriorating in custody, and claimed that he experienced "auditory hallucinations".

Guzman, who sold oranges as a child before turning to the drug trade in the 1970s, was extradited from Mexico to the United States to face drug trafficking charges there on January 19. If convicted, he is likely to spend the rest of his life in a maximum security U.S. prison.

  • Archie Newman