BANNU, Pakistan (AFP) - Pakistan Prime Minister Nawaz Sharif has urged Afghan President Hamid Karzai to help stop insurgents from escaping a major military offensive, as residents who fled the area anxiously awaited news from those left behind on Tuesday.
Mr Sharif asked his Kabul counterpart to seal their porous border along a mountainous tribal area where the Pakistani army has deployed troops and tanks in a long-awaited crackdown on insurgents.
Fresh air strikes early on Tuesday targeted three Taleban militant strongholds in Mir Ali town in North Waziristan and killed 13 alleged militants, three security sources said, raising the total insurgent death toll to 190.
The figure could not be independently confirmed and some residents who had escaped the area spoke of civilian casualties from aerial bombing before the operation was officially launched, as they awaited a break in the fighting to rescue relatives who remained behind.
Pakistan's army launched the offensive - a long-standing demand of the United States - on Sunday, a week after an attack on Karachi Airport killed dozens and marked the end of a troubled peace process.
An exodus of militants from the area had been a concern ahead of the operation, with residents and officials reporting that the majority of Taleban and foreign fighters had fled to the porous border area.
Foreign Office spokesman Tasnim Aslam said Mr Sharif had requested Mr Karzai to help stop the flow of people.
"Prime Minister Nawaz Sharif called Hamid Karzai last night to request him for the closure of Afghan border to avoid exit of militants to Afghanistan from Pakistan during the military offensive," she told AFP.
Mr Karzai's office later issued a statement asking Pakistan to take all steps to reduce civilian casualties, adding that Mr Sharif would soon send a "special envoy" to discuss the issue.
"Afghanistan is ready for any cooperation so that terrorists' sanctuaries that exist on the other side of the Durrand line be eliminated and that attacks on Afghanistan stop," the statement added.
Thousands of people have fled across the border into the Gorbaz district of Afghanistan's Khost province, according to provincial government spokesman Mobarez Mohammad Zadran, and are being provided with food and aid.
Others have made their way to the ancient town of Bannu which lies 10km to the east of the North Waziristan tribal area in the neighbouring Khyber Pakhthunkwa province.
Temperatures there are soaring to 48 deg C with up to 15 hours of power cuts owing to an ongoing national energy crisis preventing residents from using air conditioners or electric fans.
The town's bazaar was packed by tribesmen waiting for their relatives along the single road that connects Bannu to the tribal area and is currently dominated by military convoys.
Mr Laver Khan, 50, a dry fruit supplier from Datta Khel village who had arrived last week, said he had rented a house for 25 members of his family.
"At least they (the authorities) should have given us enough time to vacate our areas," Mr Khan said, telling AFP that dozens of other family members had been trapped and were now waiting for a break in the curfew to escape.
"I haven't contacted them for days, I am worried what is happening there," he added.
Mr Haji Saleem Khan, 60, who arrived from Mir Ali last week, said: "They killed women and children in the air strikes, I myself took out dead bodies from under the rubble.
"We support a real operation against militants but with this type of bombing they are killing many innocent people."
Rents in the town have gone up fivefold, residents reported, while two camps built on the outskirts lie almost unused because of the soaring heat, lack of electricity and running water.
Mr Sharif has said the offensive will usher in peace but militants vowed revenge and warned foreign companies to leave the country.
The army has deployed tanks, ground troops and jets in the area but has encountered relatively little resistance so far, with the majority of alleged militant deaths resulting from air strikes.
Pakistan's army has so far lost eight soldiers, according to officials.