PESHAWAR, Pakistan (Reuters) -- Pakistani forces have exchanged heavy fire with Taliban defending their heartland a day after launching an offensive aimed at bringing the writ of the state to lawless lands on the Afghan border.
The army said 60 militants and five soldiers had been killed in the first 24 hours of a long-awaited offensive on the global Islamist hub of South Waziristan. Soldiers were securing territory while some militants were fleeing, it said.
There was no independent verification of militant casualties.
The offensive follows a string of brazen militant attacks in different parts of the country, including an assault on army headquarters, in which more than 150 people were killed.
About 28,000 soldiers are battling an estimated 10,000 hard-core Taliban, including about 1,000 tough Uzbek fighters and some Arab Al-Qaeda members.
The militants have had years to prepare their defenses in the land of arid mountains and sparse forest cut by dried-up creeks and ravines.
The army says it has surrounded the militants in their main zone, a wedge of territory in the north of South Waziristan, and soldiers backed by aircraft and artillery are attacking from the north, southwest, and southeast.
Government forces pushing down from the north were clashing with militants in Nawaz Kot town, intelligence officials and residents said.
"There was heavy firing until midnight and in the morning I saw tanks moving in and Taliban were firing rocket-propelled grenades," said villager Gul Nawaz, who lives near Nawaz Kot.
The army has launched brief offensives in South Waziristan before, the first in 2004 when it suffered heavy casualties before striking a peace pact.
Security officials said soldiers advancing from the southwest met dogged resistance as they tried to push into the Taliban-held town of Khaisora early on October 18. Seven militants and one soldier were killed there, they said.
Soldiers moving from the southeast captured a Taliban stronghold at Spinkai Raghzai on October 17 after the militants withdrew from their fortifications and took refuge in nearby mountains, officials said.
"It is a flat area so whenever they tried to put up resistance, the helicopter gunships fired at them so they decided to flee," said a senior government official in the northwest.
In a show of unity before the offensive, government and political party leaders gave the military full backing on October 16, vowing to weed out militants.
Nuclear-armed Pakistan has been under U.S. pressure to crack down on Islamist militancy as President Barack Obama considers a boost in troop numbers fighting in neighboring Afghanistan.
Many Al-Qaeda and Taliban members fled to northwest Pakistan after U.S.-led troops ousted the Taliban in Kabul in 2001 and the region has become a global hub for Islamist militancy.
The offensive could be the army's toughest test since the militants turned on the state and it will be hoping Afghan Taliban factions elsewhere in South Waziristan and in North Waziristan stay out of the fight.
Up to 100,000 civilians have fled from South Waziristan in anticipation of the offensive, the army said, while the United Nations said 500 people were leaving every day.
Security forces are on alert across the country in case of retaliatory strikes.
Pakistani Taliban made advances towards Islamabad early this year, raising fears about the stability of the U.S. ally.
But significant military gains in the Swat valley, northwest of Islamabad, have reassured the United States and other allies about Pakistan's commitment to the fight.
The United States needs Pakistani help to disrupt militant attacks into Afghanistan, where U.S.-led forces are struggling against an increasingly potent insurgency.
U.S. officials in Washington said on October 16 the Pentagon was ramping up delivery of military equipment long sought by the Pakistani army to fight militants.