At least three people were killed and 15 others, including five soldiers, were injured when a group of people attacked a Pakistan army checkpost near the tribal North Waziristan town of Boyya.
Pakistan's army on Sunday accused two lawmakers critical of the military of playing a key role in a clash with troops at a security checkpost in which three people were killed, setting up a potential confrontation with a vast rights movement the two lawmakers helped to found.
Mohsin Dawar and Ali Wazir, parliamentarians for the volatile Waziristan region bordering Afghanistan, were among the founders of the Pashtun Tahaffuz Movement (PTM) civil rights group that has been a thorn in the side of the military with frequent sit-ins and rallies denouncing alleged military abuses.
PTM has been peaceful since its founding in early 2018 and has vowed not to respond with violence to frequent arrests and what it calls "humiliation" of its members, but some analysts have warned that some elements within PTM could turn violent if the state continued with its tough approach.
PTM's support base is mostly among ethnic Pashtuns in the Khyber Pakhtunkwa region that is still scarred by a devastating decade-long insurgency and was led by the Tehrik-i Taliban Pakistan (TTP), also known as the Pakistani Taliban.
The army said Dawar and Wazir on Sunday led a group that "assaulted" a security checkpost near the North Waziristan town of Boyya, about 16 km from the Afghanistan border.
"They wanted to exert pressure for release of suspected terrorists' facilitator arrested the other day," the army said in a statement. "In exchange of fire three individuals who attacked the post lost their lives and 10 got injured."
The military said five soldiers were also wounded in the attack, following which Wazir and eight others were detained. "Mohsin Javed (Dawar) is at large after inciting the crowd," the army said.
Dawar and Wazir could not be reached for comment.
Sources in the so-called tribal regions bordering Afghanistan said phone and internet networks in the region have been shut down and curfew imposed.
They said Dawar and Wazir were planning to stage a sit-in along with PTM members to protest against the alleged abusive treatment of a Pakistani woman by the security forces.
Dawar told Voice of America's (VOA) Pashto language radio service, Deewa, that about 30 people were wounded in the incident, including himself, and some were seriously injured.
Dawar said the security forces tried to stop protestors going through barricades and initially shot in the air but "then opened straight fire at us. Many our of people were injured," Dawar told Deewa.
PTM, which was founded to protest against the death of a Pashtun man killed by police in the southern port of Karachi, regularly draws thousands of protesters to its demonstrations against the state.