Officials citing intelligence reports and accounts from arrested fighters said more than 100 militants have died in the fighting.
Clashes continued on Monday in the North Waziristan tribal region, and thousands of residents joined an exodus out of the main town of Miran Shah.
Sikandar Qayyum, additional secretary, security, for Pakistan's tribal areas, told reporters in the northwestern city of Peshawar that based on intelligence reports and questioning of some injured and arrested militants, authorities believed more than 100 militants had been killed.
But army spokesman Major General Shaukat Sultan said he could only confirm 53 deaths, including that of five securitymen.
A militant rocket attack on a residential area for government officials meanwhile hit a house on Monday, killing a teenage girl and seriously wounding four people, Qayyum said.
Local residents are fleeing the
region to escape the fighting
The girl was the daughter of a government officer and she was killed in the official's home, an army official said on condition of anonymity because he was not authorised to make media comments.
Qayyum confirmed that army helicopter gunships had fired on militant positions around Miran Shah on Monday, while militants had attacked security checkpoints around the nearby towns of Mir Ali and Razmak.
He said there were no casualties in the militant attacks and that the situation was "comparatively under control".
"Helicopter gunships have been pounding militant positions around Miran Shah," a resident of the main town in the North Waziristan tribal region said. "The situation is very tense."
The semi-autonomous ethnic Pashtun lands along the Afghan border are Pakistan's front line in the war on terror. Many al-Qaida militants fled to the area after US and Afghan opposition forces toppled the Taliban in late 2001, and were given refuge by Taliban supporters among the Pashtun clans.
Pakistani forces have been trying to clear foreign fighters from the border and subdue their Pakistani allies since late 2004, and hundreds of people have been killed.
Fighting has continued since Saturday when gunmen launched attacks and seized government buildings in Miran Shah in revenge for the killing last week of 45 of their comrades in a government attack.
Thousands of residents have left the town since last week's violence and the exodus was continuing on Monday, the resident said.
Government forces wrested back control of most of Miran Shah on Sunday, but the militants had not given up. "There were exchanges of fire throughout the night," said the resident who, like many people in the town, is fearful of reprisals and declined to be identified.
"The firing went on intermittently with both sides using rocket-propelled grenades and missiles," he said.
Waziristan is a hot bed for pro-
The town's telephone service had been partially restored after the army took back the main exchange, which the militants seized on Saturday, and troops were in control of the main market area, he said.
Waziristan has a long history of military intervention. Britain won over some Pashtun tribes and made the region its first line of defence from perceived Russian designs on British India in the 19th century.
In the 1980s, a flood of US funded weapons and Islamist fighters poured into the area to bolster the Muslim war against Soviet forces occupying Afghanistan.
Today, Afghanistan complains of Taliban and other militants infiltrating from Waziristan and other Pakistani border areas to attack the US-backed government in Kabul and US-led foreign troops there.
Pakistan said on Sunday for the first time that militant violence in Waziristan was directly related to the Taliban insurgency.