ISLAMABAD -- An Afghan rights activist who has campaigned for girls' education has been arrested in Kabul, the United Nations said on Tuesday.

The U.N. mission in Afghanistan said Matiullah Wesa, founder and president of Pen Path -- a local nongovernmental group that travels across Afghanistan with a mobile school and library -- was arrested in the Afghan capital on Monday.

Local reports said Taliban security forces detained Wesa after his return from a trip to Europe.

The U.N. urged authorities in Kabul to clarify Wesa's whereabouts, reasons for his arrest and ensure his access to legal representation and contact with family. There was no immediate word from the Taliban on the arrest.

Since their takeover of Afghanistan, the Taliban have imposed restrictions on women's and minority rights. Girls are barred from school beyond the sixth grade and last year, the Taliban banned women from going to university.

Wesa's brother, Attaullah Wesa, said the Taliban forces surrounded their family's house on Tuesday. They beat up the Wesas' other two brothers, insulted their mother and confiscated the arrested activist's mobile phone.

Social media activists later created a hashtag to campaign for Wesa's release. Many posts condemned his detention and demanded immediate freedom for the activist.

Wesa has been outspoken in his demands for girls to have the right to go to school and learn, and has repeatedly called on the Taliban-led government to reverse its bans. His most recent tweets about female education coincided with the start of the new academic year in Afghanistan, with girls remaining shut out of classrooms and campuses.

Wesa and others from the Pen Path launched a door-to-door campaign to promote girls' education.

"We have been volunteering for 14 years to reach people and convey the message for girls education, Wesa had said in recent posts. "During the past 18 months we campaigned house to house in order to eliminate illiteracy and to end all our miseries," he added.

The U.N. special rapporteur for human rights in Afghanistan, Richard Bennett, said he was alarmed by Wesa's detention.

"His safety is paramount & all his legal rights must be respected," Bennett tweeted.

Also Tuesday, Amnesty International raised the alarm about the deterioration of human rights in South Asian countries. In a new report released Tuesday the London-based watchdog also criticized the Taliban for imposing restrictions on women and minority rights since their takeover of Afghanistan in 2021.

Peaceful protesters have faced arbitrary arrests, torture and enforced disappearance while journalists faced arbitrary arrest and detention, as well as torture and other ill-treatment for reporting that was critical of the Taliban, said Amnesty.

"Women have been at the forefront of protests in the region, often challenging patriarchal control over their bodies, lives, choices and sexuality on behalf of the state, society and family," said Yamini Mishra, the group's regional director.

The failure of South Asian countries "to uphold gender justice leaves a terrible legacy of suppression, violence and stunted potential," she added.

Meanwhile, the Islamic State group claimed responsibility for a suicide bombing near the foreign ministry in Kabul the previous day, when six people were killed and about a dozen wounded. It was the second time this year that IS staged an attack near the ministry. In mid-January, the militant group killed five people there and wounded several others.

The regional IS affiliate -- known as the Islamic State in Khorasan Province -- is a key rival of the Taliban and has frequently targeted Taliban officials and patrols, as well as members of Afghanistan's Shiite minority.

IS has increased its attacks in Afghanistan since the Taliban takeover.