An Insulate Britain protester who has been on hunger strike in prison for 13 days is being given hospital treatment, the campaign group said.
Emma Smart, 44, from Weymouth in Dorset, was moved to the hospital wing at HMP Bronzefield in Ashford, Surrey, on Friday.
She was jailed for four months on November 17 for breaching an injunction and immediately vowed to stop eating until the Government moves to insulate homes.
Ms Smart’s husband, Andy Smith, told the PA news agency that she is “feeling a bit weak but she’s still in good spirits”.
In a statement released by Insulate Britain, Smart said: “The window of my cell in the hospital wing is blocked up and there is little natural light, in my previous cell I could see the birds and trees that line the prison fence.
“I have less time to go outside in the prison yard for exercise now.
“All of this is testing my resolve to continue, but I feel that not eating is the only thing I can do from prison to draw attention to those who will have to make the choice between heating and eating this winter.”
Insulate Britain members, including Ms Smart’s husband, are to stage a 24-hour fast outside 10 Downing Street on Tuesday morning in solidarity with her, the group said.
Mr Smith, 45, told PA: “She is feeling a bit weak but she’s still in good spirits.
“I think a hunger strike is about 80% mental (strength) so as long as she’s doing OK mentally I think she’ll probably continue on her hunger strike until the Government make a meaningful statement as to whether they’re going to insulate the homes of Britain or not.”
He said his wife had been relocated to the hospital wing so that prison staff could more easily monitor her health.
“I last spoke to her yesterday but she’s recently had her telephone rights revoked so it’s increasingly difficult to speak to her,” he said, adding that it was not clear why the prison had taken the step.
Mr Smith said: “It is quite difficult, but also aware that other things are difficult.
“We’ve made difficult decisions throughout the last three years. We didn’t step lightly into making decisions to be arrested, we didn’t step lightly into making decisions not to have any children…
“There’s clearly a lot of inaction coming from our Government, they’re not taking the steps that are needed to combat the climate crisis that we’re in, and they would rather just chuck people in prison than actually face up and deal with those problems.”
Ms Smart is one of nine members of the group jailed for breaching an injunction designed to prevent the road blockades which have sparked anger among motorists and others affected by the protests.
They appeared at the High Court on November 17 after they admitted breaching an injunction by taking part in a blockade at junction 25 of the M25 during the morning rush hour on October 8.
They received sentences of between three and six months and ordered to pay £5000 in costs each.
A further nine Insulate Britain protesters are to appear at the High Court on December 14 to face a charge of contempt of court.
Insulate Britain began a wave of protests in September and supporters have blocked the M25, roads in London including around Parliament, roads in Birmingham and Manchester and around the Port of Dover in Kent.
Videos showing furious motorists dragging the climate activists away from the blockades have gone viral on a number of occasions.
The group is demanding that the Government insulate Britain’s “leaky homes” and end deaths it says are caused by winter fuel shortages.