NEW YORK (Reuters) - Mexican drug lord Joaquin “El Chapo” Guzman will remain in solitary confinement in a federal prison in New York City, a U.S. judge ruled Thursday, although he will be allowed to send pre-screened messages to his wife for personal reasons and to help mount his legal defense.

Mexico's top drug lord Joaquin "El Chapo" Guzman is escorted as he arrives at Long Island MacArthur airport in New York, U.S., January 19, 2017, after his extradition from Mexico. U.S. officials/Handout via REUTERS

Guzman’s court-appointed lawyers argued in March that he was being held in unnecessarily harsh conditions in the Metropolitan Correctional Center in Manhattan and asked that he be released into the general prison population. But U.S. District Judge Brian Cogan in Brooklyn ruled that there were good reasons for unusual measures around Guzman, who has escaped from two Mexican prisons.

“We’re extremely disappointed that Mr. Guzman and his wife will not be able to see or speak to each other,” Michelle Gelernt, one of Guzman’s lawyers, said in an email. “This is devastating news for both of them.”

She said it was “small comfort” that they would be allowed to communicate in writing.

Guzman is restricted to his cell for 23 hours a day, with the lights on at all times, and has not been allowed to speak to his wife or other family members. He has one hour of exercise in a small cage with no fresh air or sunlight, according to a March letter to prosecutors from Amnesty International.

The human rights group had asked to inspect Guzman’s cell, but Cogan on Thursday denied that request.

Guzman’s lawyers also sought more freedom to communicate with people in order to plan his defense, including his wife and potential witnesses.

Cogan ruled that Guzman may not communicate with witnesses, citing his “alleged history of witness intimidation.”

However, the judge said he may send written messages to his wife about hiring lawyers and about personal matters. Those messages will be subject to pre-screening by U.S. authorities, though not by the prosecutors in the case.

Cogan also wrote that prison staff had relayed their observations of Guzman’s visits with his attorneys to prosecutors in the past, and ordered that such communications stop.

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 Jan. 19.

In his most recent escape in 2015, Guzman walked out of prison through a mile-long, highly engineered tunnel from his cell, a sign of the huge influence he was able to wield even from behind bars.