Prominent Egyptian journalist and former activist Israa Abdelfattah has gone missing after being detained by plainclothes officers on Saturday night in the Egyptian capital, a friend who witnessed the incident said.

Meanwhile, Mostafa al-Khatib, a translator who has worked with Associated Press, was reportedly arrested on Sunday morning, according to multiple reports by human rights lawyers and journalists.

Egyptian lawyer Khaled Ali also announced that Abdallah Said, a left-wing activist and member of the small opposition party Bread and Freedom, was detained in his home on Sunday morning.

It was not immediately clear why the three figures were arrested.

Journalist Mohamed Salah, a friend of Abdelfattah, said they were both in her car at 7:30pm (17.30 GMT) on Saturday in Cairo when they were stopped by two vehicles with “armed plainclothes security officers with walkie talkies”.

“They took her into one car, and took me to the other for an hour,” he said in a Facebook post.

“After beating and blindfolding me for one hour, they dropped me on a motorway.”

Salah added that Abdelfattah has gone missing since the incident.

More than 15 hours, we still know nothing where she is being held#اسراء_عبد_الفتاح_فين #whereisesraa https://t.co/pm6eWKX2ay — Solafa Sallam (@solafasallam) October 13, 2019

In an interview with al-Hurra website, Salah said he believed Abdelfattah has been arrested due to her backing of an initiative to release political prisoners, announced on Friday by a pro-government show host.

The arrests come as the government of President Abdel Fattah el-Sisi is facing the largest public show of discontent in years.

At least 3,120 people, including well-known activists, journalists and lawyers, have been arrested since 20 September, when protests erupted over a series of corruption allegations levelled by businessman Mohamed Ali against Sisi and other top officials.

Hundreds of those arrested in the September crackdown have been released over the past week. But others - including prominent activist Alaa Abdelfattah, who is not related to Israa Abdelfattah - have faced renewed detention.

Sisi's government has led a brutal crackdown on dissent and opposition voices since coming to power in a 2013 military coup that removed Egypt's first democratically elected leader, Mohamed Morsi.

The protests that immediately followed the coup were violently put down by security forces, culminating in a massacre in Cairo's Rabaa al-Adawiya Square, where at least 1,000 demonstrators were killed.

Who is Israa Abdelfattah?

Israa Abdelfattah, 41, was one of the most iconic leaders of the 2011 revolution.

She co-founded the 6 April Movement in 2008 with Ahmed Maher to promote workers rights and rally Egyptians for a range of pro-democracy demands. She also formerly served as a project manager of the Egyptian Democratic Academy, a non-governmental organisation that promotes the use of new media tools to foster democracy and human rights.

She is currently a digital media specialist and journalist at pro-government newspaper Al-Youm Al-Sabea.

In 2015, Cairo International Airport officials banned Abdelfattah from boarding a flight to Germany, and informed her that she was officially banned from travel.

Weeks later, she learned that the ban was due to charges of “receiving illegal foreign funding” as part of investigations into the work of several Egyptian NGOs. She was not, however, summoned for interrogation or officially notified of the travel ban until October 2018, when she was interrogated in connection with the alleged foreign funding.

Abdelfattah filed a lawsuit against the travel ban, but it was upheld by the Cairo Administrative Court in June 2015.