Two persons were arrested, vehicles seized and shops sealed as the authorities pressured Pashtun tribesmen for the surrender of 12 of their community members, suspected of harbouring Taliban and al-Qaida members.

The action followed a similar operation against another tribe that had been asked by the authorities to hand over three tribesmen for the same offence.

The tribesmen have had the heat turned on them ever since the Pakistani military arrested 18 al-Qaida and Taliban suspects and killed eight others last week after a raid in the South Waziristan tribal area.

So far, 38 tribesman have been arrested, but none of the 15 men wanted by the government have been found.

The crackdown marks a departure from Pakistan's earlier reluctance to act against the conservative and heavily armed tribes.

Also during the day, government and military officials from Afghanistan, the US and Pakistan met in the Pakistani city of Rawalpindi to discuss cooperation in operations in the border area.

So far, 38 tribesman have been arrested, but none of the 15 men wanted by the government have been found.

Afghan appreciation

Afghan Foreign Ministry spokesman Omar Samad said his government welcomed Pakistan's latest operations.

"We are just witnessing some qualitative change in Pakistani operations in the tribal regions against terrorist elements, which is a positive sign and encouraging sign that needs to be continued and not be limited for any reason whatsoever," he said.

Muhammad Azam Khan, the Pakistani administrator of the South Waziristan tribal agency said authorities would continue to pressure the tribes to surrender the wanted men.

Provincial authorities say tribal leaders have violated an agreement reached with the government in May that they would deny sanctuary to "aliens".

Laws which govern Pakistan's tribal areas allow collective punishment of tribes if they fail to maintain order.