Inmates' lawyers say health of men is at risk amid allegations prisons are using cold temperatures to snuff out protest

Prison guards are trying to break a hunger strike involving thousands of prisoners in California by blasting cells with cold air, confiscating legal documents and, in one case, banning lawyers, according to legal representatives and relatives.

Authorities have taken the action, it is alleged, in retaliation for a strike which entered its 12th day on Friday, piling pressure on the state's troubled penal system. Lawyers say the health of the men is being put at risk.

An estimated 30,000 inmates in 33 jails launched the hunger strike on 8 June, the biggest in the state's history, to protest against solitary confinement and other conditions they said amounted to torture.

At any one time, California holds about 12,000 inmates in extreme isolation, including some who have been in windowless boxes known as security housing units (SHUs) for decades. Guards say it is a vital tool to tame gang violence.

The California Department of Corrections and Rehabilitation (CDCR) said on Thursday the number of strikers had fallen to 1,457 inmates in 15 jails. Inmates' lawyers and relatives said more than 2,000 were still refusing food. Hundreds are also boycotting work and classes.

Anne Weills, a civil rights attorney who this week visited Pelican Bay state prison, which is at the heart of the protest, said the temperature at the prison had been deliberately lowered. "They are the upping the ante in terms of cold. It's clearly a tactic to make everything uncomfortable and in essence retaliate for the hunger strike," she said. "They are freezing, these men. I could see them shivering in front of me. I had two sweaters on and I was freezing."

The cold was badly affecting smaller, thinner prisoners with little body fat, especially those weakened by their fast, she said. "They are suffering. This puts them at risk of hypothermia."

Terry Thornton, a spokesperson for the CDCR, denied the temperature at Pelican Bay's segregated units, where many strike leaders are held, had been lowered. "The temperature is between 72 to 73 degrees, which is normal."

Weills and others disputed that. Alfred Sandoval, an inmate in solitary confinement at Pelican Bay, said in a postcard to his wife guards had "turned the blowers on" just as they did in 2011, during a previous hunger strike.

"It is definitely happening, it's retaliation," said Kamau Walton, a member of Prisoner Hunger Strike Solidarity Coalition. The group repeated the claim on its website.

California's governor, Jerry Brown, has gone on vacation, denting hopes of a quick resolution to a protest which has united black, Latino and white inmates, including members of racist gangs.

The principal grievance is California's unusual policy of indefinitely putting suspected gang members in solitary and moving them back into the regular jail only if they identify fellow gang members.

Danny Murillo, 33, who spent five years in solitary confinement, said it was a form of sensory deprivation which left him disorientated, even after he was released. "I felt very uncomfortable around people."

Additional demands include an end to group punishment, an overhaul to the policy of identifying suspected gang members as well as better food, education and rehabilitation programmes.

This week authorities moved 14 leaders from secure housing units to administrative segregation, a more complete form of isolation known as Ad-Seg. In a published statement they called it a "diabolical" attempt to break their resolve and hasten their deaths but vowed to continue. "We are 100% committed to our cause and will end our peaceful action when CDCR signs a legally binding agreement to our demands."

Guards seized private legal documents while moving the men, including one outlining their possible terms for a negotiated settlement, said Weills. "It's an incredible violation of client-attorney privilege. It's unconscionable."

Authorities temporarily banned another attorney, Marilyn McMahon, a member of the mediation team, from state jails, citing an unspecified threat from a member of her advocacy group California Prison Focus. She was also banned during the 2011 strike. McMahon said it was an attempt to sever communications between prisoners, their attorneys and the outside world.

Thornton, the penal service spokesperson, said the confiscated documents were returned unread.

She said the inmates who were moved had been warned of repercussions. "There are consequences for engaging in disruptive behaviour and a mass hunger strike is disruptive behaviour."

The vast majority of inmates were not participating in the strike, she said, and authorities wanted to minimise disruption for them. The strike, she added, was wasteful. "Lots of taxpayer-funded food is being thrown away."

The strike has renewed a call for architects to refuse to design execution chambers and solitary confinement cells. Raphael Sperry, who heads Architects/Designers/Planners for Social Responsibility launched the campaign last October.

The San Francisco chapter of the American Institute of Architects endorsed the measure and the New York chapter is considering it.

Sperry visited Pelican Bay earlier this month. "What struck me is that the whole building was designed to eliminate social contact. Studies show that that undermines people's psyches. We have to say we're never designing these buildings again."