The possible death in prison of imprisoned British-Egyptian dissident Alaa Abdel Fattah is “in nobody’s interest,” said his sister Sanaa Seif, almost two days after he began refusing water.

After a seven-month hunger strike during which he was on just 100 calories a day, Abdel Fattah stopped drinking water on Sunday to coincide with the opening of the UN climate summit COP27 in Egypt.

Widely regarded as Egypt’s most prominent dissident, he was sentenced to five years in prison for “spreading false news” after spending most of the past decade behind bars.

“We are talking about an innocent man who has unjustly spent nine years in prison,” Seif said of the climate summit in the Red Sea resort of Sharm el-Sheikh, where she had traveled to appeal to world leaders to press for his release.

Seif, her sister Mona, her mother Laila Soueif and her aunt, the acclaimed writer Adhaf Soueif, have campaigned worldwide for the release of the activist, who gained British citizenship in April through his British-born mother.

“We need sensible people to intervene,” Seif said in an interview with AFP. “I put my hopes in the British delegation because, as his sister, I cannot give up or tell myself that my brother is going to die.”

Acknowledging the risk of traveling to Sharm el-Sheikh with its heavy security restrictions, she said: “I admit I was afraid to come.”

“But it’s our last resort,” she said.

“I came so that Alaa would not be forgotten. I would like to remind both Egyptian and British officials that my presence means someone is dying and it is possible to save them.”

British Prime Minister Rishi Sunak raised the case of Abdel Fattah at a meeting with his Egyptian counterpart Abdel Fattah al-Sisi on Monday and “stressed the British Government’s deep concern on this matter,” a Downing Street spokesman said.

Sunak said he “hopes this will be resolved as soon as possible and will continue to push for progress,” the spokesman said.

Amnesty International chief Agnes Callamard warned Sunday that “there isn’t much time – 72 hours at best,” referring to Abdel Fattah’s potential remaining lifespan.

But Egyptian Foreign Minister Sameh Shoukry assured in an interview with CNBC on Monday that the dissident “benefits from all necessary care in prison”.

Seif nonetheless warned that “the way his case is being handled only hastens the destabilization of the regime”.

She accused Egypt of using the COP27 summit to “erase its bad human rights record”.

But despite a crackdown, Abdel Fattah’s cause was championed during the summit by activists, artists, right-wing defenders and politicians – including the French president.

Frenchman Emmanuel Macron said on Monday he had received assurances from Sisi that the Egyptian President was “committed to ensuring that (the) health of Alaa Abdel Fattah is preserved”.

It came as concerns about his condition continued to grow.

On Monday morning, “my mother went to wait outside the jail to check on him after 24 hours without water,” Seif said.

By evening she still had received no word from her son, nor had she been able to deliver the clothes and books she brings him each week.

“The ball is in the politicians’ hands, it’s up to them to do their job,” Seif continued.

“We continue the fight and must not lose hope.”