The family of jailed British-Egyptian pro-democracy activist Alaa Abdel Fattah have demanded authorities in Cairo provide proof he is still alive.

They have not heard from him since he escalated his seven-month hunger strike on Sunday by refusing water.

His sister told the BBC that it felt as if they were "dealing with a complete black hole", with the UK government also unable to provide any information.

UK Prime Minister Rishi Sunak said his case grew "more urgent by the day".

He told the House of Commons on Wednesday that he had spoken to Egyptian President Abdul Fattah al-Sisi at the COP27 climate summit in Sharm el-Sheikh and would continue to press the Egyptian government to "resolve the situation".

"We want to see Alaa freed and reunited with his family as soon as possible," he added.

However, when pressed by Labour leader Keir Starmer on whether any progress had been made in securing Abdel Fattah's release, Mr Sunak did not provide an answer.

On Tuesday, UN human rights chief Volker Türk and German Chancellor Olaf Scholz also urged Egypt to release Abdel Fattah immediately.

"Abdel Fattah is in great danger. His dry hunger strike puts his life at acute risk," Mr Türk warned, describing him as one of a number of people in Egypt who had been "arbitrarily deprived of their liberty and incarcerated after unfair trials on multiple occasions".