Islamabad, Pakistan - Police in Pakistan have detained a member of parliament and at least 24 others at a demonstration calling for the release of a prominent Pakistani rights activist, a further step in its crackdown on the Pashtun Tahaffuz Movement (PTM) rights group.

On Tuesday, thousands took to streets across Pakistan to protest the arrest of activist Manzoor Pashteen who accuses the country's military of human rights abuses.

Witnesses said police scuffled with protesters in the capital, Islamabad, when they attempted to lead a short march following speeches at the demonstration.

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"The police just sort of attacked the protesters," said Khushal Khan Khattak, a protester. "I ran towards my father thinking he was hurt. He was fine. I saw them dragging away Mohsin [Dawar]."

Dawar, a prominent PTM leader, is a member of Pakistan's lower house of parliament. He was elected from the northwestern North Waziristan district.

Video footage from the protest showed him being dragged by the police and detained in a police vehicle.

Other prominent activists to be arrested included Ammar Rashid, the provincial leader of the leftist Awami Workers Party (AWP), and Ismat Shahjahan, another AWP leader.

Police confirmed to Al Jazeera that at least 25 protesters were detained but provided no further details.

Protest leaders who managed to escape claimed the police used force to round up demonstrators.

"They were handling people roughly [and] they were forcibly putting them into the vans," said Afrasiab Khattak, a former senator who addressed the protest before the police action.

Similar protests in Karachi, Pakistan's largest city, and Lahore drew hundreds of demonstrators and concluded peacefully on Tuesday.

Charges of sedition

The demonstrators' main demand was the release of Pashteen, who was arrested in a midnight raid on Monday by police in the northwestern city of Peshawar.

Pashteen is charged with committing "sedition" and "criminal conspiracy" during a speech at a PTM rally in the northwestern city of Dera Ismail Khan earlier this month.

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On Monday, a Peshawar court rejected his application for bail and ordered he be transferred to Dera Ismail Khan.

The PTM shot to prominence in 2018, when it championed the cause of Naqeebullah Mehsud, a young garment trader who was shot dead by police who claimed he was a fighter allied with the Islamic State of Iraq and the Levant (ISIL, or IS).

Subsequent investigations revealed no such links.

The PTM's primary demands centre around putting an end to enforced disappearances, extrajudicial killings and heavy-handed security policies in the country's northwest, where the military has fought the Pakistani Taliban for years.

Since last year, the PTM has faced increasing restrictions on its activities. Coverage of the group's protests faces an almost blanket ban in Pakistan's local press, and leaders have routinely been accused of "sedition" and arrested.

In May, a clash between PTM supporters and the military at a checkpoint in North Waziristan saw at least three protesters killed and several other people - including at least five soldiers - injured.

Dawar, the PTM leader and member of parliament, and Ali Wazir, another PTM leader and elected member of parliament, were arrested in connection with that attack and kept in custody for more than three months.

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