The United Nations human rights office called on Egypt on Friday to free a prominent blogger, lawyer and journalist allegedly mistreated in custody who are among several thousand people detained since street protests began a month ago.

Officials at Egypt's interior ministry were not immediately available for comment. The state prosecutor's office said in late September that it had questioned up to 1,000 suspects who took part in the demonstrations.

About 3,400 people have been arrested since protests began, including about 300 who have since been released, according to the Egyptian Commission for Rights and Freedoms, an independent body.

"Unfortunately, such arrests are continuing, and have included a number of well-known and respected civil society figures," UN human rights spokeswoman Ravina Shamdasani told a news briefing.

Protests against President Abdel Fattah el-Sisi in Cairo and other cities have followed online calls for demonstrations against alleged government corruption.

Sisi, first elected in 2014 after, while army chief, leading the 2013 overthrow of President Mohamed Morsi, has overseen a crackdown on dissent ranging from liberal to hardline groups - the most severe in recent memory, rights groups say.

Hunger strike

Journalist and activist Esraa Abdelfattah was arrested by plain-clothes security officers in Cairo on October 12 and was reportedly beaten after she refused to unlock her mobile phone, Shamdasani said. Abdelfattah is on a hunger strike, she added.

Alaa Abdel Fattah, a blogger and software engineer, was released in March after serving a five-year sentence for protesting without permission, but was re-arrested on Sept. 29, Shamdasani said. The same day, his lawyer, Mohamed el-Baqer, was arrested while attending the interrogation, Shamdasani added.

Abdel Fattah was struck by guards on his back and neck while being forced to walk down a corridor in his underwear, while el-Baqer has been subjected to physical and verbal abuse, and denied water and medical aid, she said.

Ivan Surkos, the European Union's ambassador to Egypt, tweeted on Tuesday that he had raised concerns over individual detained activists with Ahmed Gamal Eddin, assistant foreign minister for human rights.

"Will my messages end as [a] dialogue of deaf persons? Let's hope not," Surkos said.