A demonstrator holds up his chained hands as journalists and members of the April 6 movement protest in Cairo this week against the restriction of press freedom and arrests of reporters and activists ahead of a planned general strike. (Mohamed Abd El Ghany/Reuters)

They have been taken from their homes, the streets, even from schools. Some have turned up dead, while others have just vanished.

They are Egypt’s disappeared: dozens of students and activists kidnapped in what human rights advocates say is an escalation of the government’s campaign against dissent.

Egyptian activists say they have documented a disturbing rise in forced disappearances over the past two months, cases in which victims are taken without warrants and police deny knowledge of their whereabouts. The detainees often show up later in court or are released without explanation. At least two who were recently seized by security forces were later found dead, according to rights groups.

“People have disappeared in Egypt before but definitely not at this rate,” said Khaled Abdel Hamid, spokesman for the rights group Freedom for the Brave.

The group says that security forces have kidnapped 163 people since April and that 64 of them have since been released.

Another rights organization, “3adala” (Justice), said it had confirmed 91 disappearance cases in April and May and that 38 people are still missing. The discrepancy in the tallies is attributable to different verification methods and contact networks, as well as the opaque nature of Egypt’s security apparatus, activists say.

Last month, the Cairo-based Alkarama rights group announced that it had asked the U.N. Working Group on Enforced or Involuntary Disappearances to intervene in connection with seven cases of forced abductions in Egypt. The U.N. group has said in statements that it has sought since 2011 to visit the country but that Egyptian authorities have not responded to its requests.

The Interior Ministry did not respond to repeated requests for comment about the allegations of mass detentions.

“We normally find out [about the abductions] through witnesses” who report seeing people dragged away by police or plainclothes agents on the streets or from their homes, Abdel Hamid said.

In one instance, he said, a woman watched as Ahmed al-Ghazali, a member of the left-leaning April 6 Youth Movement, was detained by men she presumed were plainclothes police officers. During a melee in which Ghazali was shoved into an unmarked van, according to the woman, his phone fell out of his pocket. The woman picked it up and used it to contact his friends and family, the activist said.

Other times, sympathetic police officers leak information to relatives or lawyers searching for the missing. Sometimes, fellow prisoners with access to a lawyer spot the missing detainees and help get word out to the community of activists.

Authorities don’t normally alert relatives when a missing detainee is about to appear before a judge. According to Abdel Hamid, rights groups, with their webs of contacts, often receive anonymous phone calls notifying them that a disappeared person is about to turn up in court.

In recent weeks, the detainees who have seen a judge have been charged with engaging in unlawful political activities or demonstrations. The suspects are often appointed a public defender.

The now-banned April 6 Youth Movement had called for a general strike on June 11 to protest Egypt’s deteriorating economic conditions. Many of its leaders have been targeted for arrest, rights groups say.

“It’s a scare tactic to keep people in line,” Abdel Hamid said of the disappearances.

The state’s increased offensive against its political opponents started in the summer of 2013, when the military ousted the elected president, Mohamed Morsi — a response to massive street protests against the Islamist leader’s rule.

But Morsi’s overthrow polarized the country. His supporters demonstrated in the streets, and security officers responded forcefully, gunning down unarmed protesters on several occasions. President Abdel Fatah al-Sissi, who was defense minister at the time, gained widespread support for his bid to crush the Muslim Brotherhood, from which Morsi hailed.

But the crackdown soon widened to include secular and leftist activists as well as rights advocates and employees of nonprofit groups. In the months after Sissi’s takeover, from July 2013 to May 2014, the government detained, charged or sentenced more than 41,000 people, according to Human Rights Watch.

Egypt is experiencing “repression the likes of which it hasn’t seen in decades,” Joe Stork, the deputy Middle East and North Africa director for Human Rights Watch, said in a statement this past week. The New York-based group said Sissi “has provided near total impunity for security force abuses . . . and severely curtailed civil and political rights.”

When freelance photographer Esraa al-Taweel disappeared June 1, her father feared the worst. She had left her house in a Cairo suburb to have dinner with two friends, he said. But neither she nor her companions returned home.

Her family launched a frantic search for Esraa, 23, who was crippled last year when security forces shot her as she was photographing a demonstration. They ended up at a local police station.

“They told us she was not there,” said her father, Mahfouz al-Taweel.

But several low-ranking police officers later whispered to him that she had indeed been detained, he recounted. Some activists say they suspect that police may have arrested her because she had a camera, which she often carried with her.

“They said the officers would never tell us,” Taweel said of the police recruits.

“She is handicapped and needs treatment,” he added. “I just want to know where my daughter is.”

On Thursday, Freedom for the Brave received information that one of Esraa’s companions, a student named Omar Ali, had been seen at the maximum-security Aqrab prison outside Cairo by a fellow detainee. Word was spread through trusted sources and surreptitious phone calls, the activists said. The group has been unable to determine what Ali might be charged with.

“In my entire career as a lawyer, I had never encountered [forced disappearances] until now,” said Amro Hassan of the Cairo-based Association for Free Thought and Expression, a nongovernmental group that advocates freedom of expression in Egypt. “I’m still trying to understand it.”

Mohamed Zarea is the head of the Human Rights Association for the Assistance of Prisoners and has defended and assisted detainees for nearly two decades. He said he dealt with 40 cases of forced disappearances in the mid-1990s, when Egypt was grappling with a violent Islamist insurgency.

“Most of the people who disappeared were radical Islamists,” he said, adding that the victims vanished for years at a time — or in some cases were never found. “What happens now is someone is kidnapped and then sent to court later on trumped-up charges.”

The periods during which the current detainees disappear are much shorter, he said.

In online spreadsheets and on Facebook, activists have circulated lists of those who have reportedly gone missing over the past two months. They include young and old, teachers and students, fathers and sons.

“Taken into a microbus and detained,” one entry reads.

Another, compiled by the prominent activist Mona Seif, catalogues the arrest of the family of April 6 Youth Movement member Nour al-Sayyed Mahfouz.

“All three blindfolded & detained from their home,” it reads, referring to Mahfouz, her father and her brother. In a news story linked to the entry, Mahfouz’s mother says the police took the three.

There is a June 1 note on the Sinai-based rights activist Sabry al-Ghoul: “Reportedly died after being detained by the military.”

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Today’s coverage from Post correspondents around the world