Rights activist Gulalai Ismail on Thursday thanked Prime Minister Imran Khan "for ensuring [her] release" after she was detained for 30 hours following a protest outside Islamabad Press Club earlier this week.

Ismail and 17 others associated with the Pashtun Tahaffuz Movement (PTM) were arrested by Islamabad police on Tuesday and detained after they participated in the protest demonstration.

PTM is a rights-based alliance that, besides calling for the de-mining of the former tribal areas and greater freedom of movement in the latter, has insisted on an end to the practices of extrajudicial killings, enforced disappearances and unlawful detentions, and for their practitioners to be held to account within a truth and reconciliation framework.

Ismail was released on Wednesday night, but the others who were arrested remain in police custody.

In a series of tweets posted hours after she was freed from Adiala jail, Ismail said: "Thank you Prime Minister Imran Khan for ensuring my release. These were tedious 30 hours for my family. Please help to bring out our other 17 friends."

She also called upon the prime minister to hold those "accountable who are dismantling our constitutional rights".

"Only holding those accountable who are dismantling our constitutional rights can bring prosperity to this country. Stronger parliament, stronger Pakistan," she tweeted.

Ismail also praised Human Rights Minister Shireen Mazari for "support and "tremendous efforts in finding [Ismail]".

She reminded Mazari that 17 activists were still in custody, adding that: "[their] constitutional rights are getting violating at the whim of unknown."

Talking to DawnNewsTV, the activist said that after being arrested on Tuesday, she was first detained in a women's police station in Islamabad. The next morning, she was shifted to a women's hostel and then taken to the Aabpara police station, from where the arrested were taken to Adiala after a five-hour wait.

On Wednesday night, she was brought back to the women's police station in Islamabad, where she had been initially held and subsequently released. The rights activist said that the police still had not returned her phone and were misleading her by telling her she could get it from one police station or the other.

She alleged that the police had "continuously misguided" her family by telling them that Ismail had been detained by the intelligence agencies.

"I was in the custody of the police," she said.