Islamabad, Pakistan - Pakistani police say they have arrested prominent rights activist Manzoor Pashteen, the leader of the Pashtun Tahaffuz Movement (PTM), which is known for its strident criticism of the country's powerful military for alleged enforced disappearances and extrajudicial killings.

Pashteen was arrested late on Sunday from the Shaheen Town area of the northwestern city of Peshawar, police official Nabibul Khan told Al Jazeera.

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"He was required in a case by the police from Dera Ismail Khan city police station, so we [arrested him]," said Khan.

According to the police report, he was arrested on sedition charges.

As the PTM rose to prominence through nationwide rallies, police routinely filed cases alleging Pashteen and other PTM leaders committed sedition in their speeches.

However, it is the first time Pashteen has been arrested in such a case.

Mohsin Dawar, a PTM leader and member of parliament, confirmed the arrest to Al Jazeera.

"This is our punishment for demanding our rights in a peaceful [and] democratic manner," Dawar said in a Twitter post on Monday. "But Manzoor's arrest will only strengthen our resolve."

Pashteen, in his 20s, and a small group of other young activists who had been displaced by the Pakistani military's war against the Taliban in their native South Waziristan, founded the PTM in Dera Ismail Khan, located about 250km south of Peshawar.

They shot to national prominence in 2017 when the group championed the cause of Naqeebullah Mehsud, the victim of an extrajudicial killing by a notorious Pakistani counterterrorism police officer.

Since then, Pashteen has led rallies of thousands across the country, demanding justice for other victims of enforced disappearances, extrajudicial killings and alleged torture while in security forces' custody.

His group has also demanded that the Pakistani military clear the country's northwestern tribal districts - the site of the war against the Pakistan Taliban since 2007 - of all land mines and other unexploded ordnance.

'Funded by foreign intelligence services'

The group has long been in the crosshairs of Pakistan's military, which has directly ruled the country for roughly half of its 73-year history and still holds control over security and foreign policy.

Coverage of PTM rallies and Pashteen's statements is regularly censored across Pakistani news media.

In April, the military warned the PTM that its "time is up", accusing the group of being funded by foreign intelligence services. PTM denies the charges and has invited the military to make its evidence of any such funding public.

A month later, a PTM rally clashed with security forces at a checkpoint in the northwestern district of North Waziristan. Soldiers fired into the crowd, killing at least three people, rights activists say.

Police registered a terrorism case against Dawar, the member of parliament, who was leading the rally and spent days in hiding following the violence.

He was eventually arrested, alongside fellow PTM leader and Member of Parliament Ali Wazir, and held for three months before being released on bail for lack of evidence against them.

Asad Hashim is Al Jazeera's digital correspondent in Pakistan. He tweets @AsadHashim