The mother of a British-Egyptian activist imprisoned in Cairo has been admitted to hospital for the second time, a week after resuming a full hunger strike to campaign for his release, her family says.

Laila Soueif, 69, the mother of Alaa Abdel Fattah, was taken to Guy’s and St Thomas’ hospital in London on Thursday with dangerously low blood sugar and blood pressure. She is refusing glucose treatment.

She began consuming only tea, coffee and rehydration salts in September.

She moved to a partial strike in February, consuming 300 calories a day, after she was admitted to hospital for the first time and the British prime minister said he had “pressed” Egypt’s president to free her son.

Despite having lost more than 40% of her original body weight, Ms Soueif announced on 20 May that she had decided to return to a zero-calorie diet because “nothing has changed, nothing is happening”.

Two days later, Prime Minister Sir Keir Starmer said he had again pressed Egyptian President Abdul Fattah al-Sisi for the urgent release of her son, and “underlined how important it is to him to bring an end to the anguish Alaa and his family have faced”.

Alaa Abdel Fattah is also on his 91st day of his own hunger strike – consuming nothing but herbal tea, black coffee and rehydration salts, like his mother, at Wadi al-Natrun prison in Egypt, according to the family.

The 43-year-old blogger and pro-democracy activist is one of Egypt’s best known political prisoners.

He was arrested in September 2019, six months after finishing a previous five-year sentence.

He was convicted in 2021 of “spreading false news”, for sharing a Facebook post about torture in Egypt.

He should have been released on 29 September 2024 – the day Mrs Soueif started her hunger strike. However, the Egyptian authorities refused to count the more than two years he spent in pre-trial detention towards his time served.

Although he acquired British citizenship in 2021, Egypt has never allowed him a consular visit by British diplomats.

In a statement issued on Friday, Mrs Soueif’s family said her blood sugar levels had “dropped to a shocking new low of 1.1 mmol/L” overnight.

The levels rose to 2.7 mmol/L after she was given glucagon – a natural hormone used to treat severe hypoglycaemia – but quickly dropped back down to 1.4 mmol/L, they added.

Her daughter, Mona Seif, wrote on X: “No-one here comprehends the numbers, that she is still conscious and adamantly refusing medical intervention.”

Eilidh Macpherson of Amnesty International UK said: “It should never have come to this. Alaa is a prisoner of conscience, he shouldn’t have spent a single minute behind bars, and his mother shouldn’t have had to spend a minute on hunger strike to campaign for his release.

“The UK government must use all of the tools at its disposal to step up the pressure on President Sisi to release Alaa, including through further direct calls.”

On Wednesday, a UN panel of independent human rights experts said in a legal opinion that Alaa Abdel Fattah’s detention was arbitrary and illegal under international law, and called for his immediate release, his lawyer said.

The UN Working Group on Arbitrary Detention (UNWGAD) determined that he was arbitrarily arrested for exercising his right to freedom of expression, was not given a fair trial and continued to be detained for his political opinions.

According to the panel, the Egyptian government said he was afforded “all fair trial rights” and that his sentence would be completed in January 2027.