A prisoner linked to Palestine Action who is on day 71 of a hunger strike has told a friend: “I’m dying.”

Francesca Nadin visited Heba Muraisi, 31, at HMP New Hall, in Wakefield, on Saturday for the first time since the protest began and said she was taken aback by her friend’s appearance.

“I was shocked – I mean I shouldn’t be – at how skinny she is, like a paper thing,” said Nadin. “When I hugged her I felt like if I hugged too hard I would just break her. She has to wear a face mask at the moment because her immune system’s so low, but despite that I could see how her eyes were sunken … She said that she actually struggles to sit down for long periods of time now, because she’s lost all her fat, she’s just sitting on her bones basically.

“She’s dying. She said it: ‘I’m dying.’ Her body’s shutting down. I know mentally she’ll remain strong right to the last moment but she is dying. The government by putting her in prison and denying her all her rights they’re not just letting her die, they’re actively killing her.”

Muraisi has said she is suffering from chest pains and “twitches on the side of her chest”, raising fears that she may be at risk of heart failure. Fellow hunger striker Kamran Ahmed, 28, who is on day 64, has been told by doctors that he is suffering from heart muscle shrinkage, with his heart rate dropping to 40 beats per minute and is at risk of sudden cardiac arrest, his sister has said.

Lewie Chiaramello, 22, who has type 1 diabetes, is fasting every other day for 44 days. On Saturday, Umar Khalid, 22, one of five prisoners to have previously paused participation in the hunger strike, restarted.

Their key demands are a fair trial, immediate bail (all will will have spent more than 18 months in prison before trial relating to Palestine Action-related activities), deproscription of Palestine Action, closing down the UK sites of the Israeli arms company Elbit Systems and ending censorship of the prisoners’ communications.

Other demands include that Muraisi is moved back to HMP Bronzefield, as HMP New Hall, where she was transferred to last year, is hundreds of miles away from her family and support system.

Nadin, said that when she was on remand for involvement in a Palestine Action protest she spent time in the same cell Muraisi now inhabits, and that supporters of the hunger strikers “wake up every day full of dread, full of pain and sadness”.

On Monday, the authors Naomi Klein, Angela Davis, Judith Butler, Sally Rooney, Kamila Shamsie and China Miéville joined global scholars in a statement of solidarity for the hunger strikers. In an echo of the slogan that was on the placard Greta Thunberg was carrying when she was arrested on 23 December, it simply says: “We oppose genocide, we support the Palestine Action prisoners.”

Prof Peter Hallward, of Kingston University, one of dozens of academic signatories of the statement, said: “The UK is now perilously close to full descent into authoritarian rule. Ministers won’t even meet with hunger strikers who are now at death’s door. [They] seem perfectly ready to let this country’s most committed and courageous opponents of an ongoing genocide waste away and die.”

The government has been approached for comment.