Authorities in Pakistan's tribal area of South Waziristan have made more arrests in their crackdown on suspected al-Qaeda sympathisers.
The crackdown follows an operation on the Afghan border last week
About 40 people have now been detained, according to Syed Anwer Ali Shah, a government official in the regional capital, Wana.
The crackdown has been extended from two tribes - the Kari Khel and Desi Khel - to include a third, the Yargul Khel.
Tribesmen have been ordered to hand over three elders who are accused of providing shelter in their homes to al-Qaeda suspects.
In an operation on the Afghan border last week, the Pakistani army killed eight al-Qaeda and Taleban suspects and arrested 18.
Two Pakistani soldiers also died in one of the army's fiercest exchanges with al-Qaeda and the Taleban.
Authorities gave the tribes a deadline of Tuesday night to hand over three tribal elders, identified as Payo Khan and Zari Gul of the Kari Khel and Noor Islam of the Desi Khel.
When the deadline expired, the authorities moved in to make arrests and to close shops and businesses.
Mr Shah said the "economic blockade" would continue and that tribesman who refused to co-operate risked having their homes demolished.
"We will carry on with the operation in the South Waziristan area until the men we are looking for are handed over to us," he said.
Mr Shah said the authorities received information that the Yargul Khel was also involved in sheltering al-Qaeda suspects and five arrests from that tribe had been made.
The authorities say tribal leaders have violated an agreement reached with the government in May last year that they would deny sanctuary to "aliens".
In Islamabad, lawmakers from the tribal region expressed their opposition to the crackdown.
Maulana Abdur Rashid, a member of Pakistan's National Assembly, said: "We demand that the government immediately halts the operation."
In last week's operation at the border town of Angor Adda, the army's elite Quick Response Force fought for 14 hours with militants, who replied with grenades and machine-gun fire.