There has recently been a "significant escalation" in Egypt's crackdown on social dissent, the UN said on Tuesday, warning that arbitrary detention in the country had become a "chronic problem".Since 2013, international human rights groups have criticised President Abdel Fattah al-Sisi's government for cracking down on secular and left-wing activists, as well as Islamists close to the banned Muslim Brotherhood.But the UN rights office warned on Tuesday of a "renewed campaign of arrests, interrogations and detentions of activists, bloggers and journalists in Egypt" in recent weeks.This "appears to indicate a significant escalation in the crackdown against the rights to freedom of expression, association and assembly in the country," spokesperson Ravina Shamdasani told reporters in Geneva.She said a long line of prominent bloggers, journalists, lawyers and activists were among those who had been detained in the weeks since Egypt's General Prosecutor in February ordered prosecutors to monitor social media sites that "spread lies and fake news".The growing crackdown also coincided with March elections that gave Sisi an official 97% of the vote. He was sworn in for his second four-year term last Saturday.Personalities involved in the January 2011 popular uprising that brought down president Hosni Mubarak are among those who have been detained, including blogger and journalist Wael Abbas and Shadi Ghazali Harb one of the youth leaders during the 2011 revolution.In many of the recent cases, those arrested were not presented with a warrant, the UN said."We are extremely concerned that arrests like this, often followed by harsh sentences, and often for simply exercising the rights to freedom of opinion, expression and assembly, have become commonplace," Shamdasani said."Arbitrary detention has become a chronic problem in Egypt." She stressed that the cases she was raising were only the "prominent cases ... which have come to the attention of the United Nations. Certainly there must be many other cases".The UN rights office, she said, is calling on authorities in Cairo "to fully ensure the rights of all detainees to their physical and psychological integrity, and to due process".She also called for "the immediate and unconditional release of all those currently being held by the Egyptian authorities for the legitimate exercise of their human rights".* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook.