Several high-profile figures, including the actor Emma Thompson and Nobel laureate Kazuo Ishiguro, have supported the family’s campaign, along with the Swedish environmental activist Greta Thunberg, who joined their protest in London last month.

Thunberg said Sunday that she was boycotting the COP27 summit because of Egypt’s human rights record.

After speaking with the sisters on the phone, James Cleverly, Britain’s foreign minister, tweeted that the U.K. would “continue to work tirelessly for his release.”

But Seif said the U.K. government “didn’t seem to have an action plan,” and she was hoping COP27 — where Prime Minister Rishi Sunak arrived early Monday — would be used to highlight the plight of political prisoners in Egypt.

“Regardless of how it ends, Alaa has already won this battle,” Seif said.

NBC News has emailed the Egyptian Ministry of Justice about the allegations made about the treatment of Alaa Abdel Fattah.

Public protests have been effectively banned in Egypt, following a brutal clampdown on political dissent that began with the overthrow of Muslim Brotherhood leader and former president Mohammed Morsi in 2013, by el-Sisi, who was army chief at the time.

After he was elected president the following year, Sisi said these security measures were needed to stabilize his country, and a subsequent crackdown swept up liberal activists as well as Islamists.

Since then, little has changed, human rights groups say.

‘Greenwashing’ a government crackdown

Environmental activists are among the tens of thousands of people, including political protesters and journalists, who have been languishing in Egyptian prisons for years, many without trial, according to Human Rights Watch, an international nongovernmental research and advocacy organization.

Basing his opinion on recent interviews conducted with people inside Egypt and other data, Richard Pearhouse, Human Rights Watch’s environment director, said by telephone Friday that the violent repression of civil society includes the “jailing and harassment of environmental activists and restrictions on groups researching the impact of climate change in the country.”

“The Egyptian government has imposed arbitrary funding, research and registration obstacles that have debilitated local environmental groups, forcing some activists into exile and others to steer clear of important work,” he said.