KABUL, Afghanistan - U.S.-led coalition and Afghan forces clashed with Taliban fighters in southern Afghanistan, killing 24 suspected militants, while three more died in an ambush in the west, the coalition said Thursday. ADVERTISEMENT

Pakistani troops, meanwhile, fired at Afghan soldiers as the Afghans pulled up a disputed fence supposed to prevent Taliban militants from crossing their common border, the Afghan Defense Ministry said.

While there were no reports of casualties, the incident marks an escalation in the battle between Kabul and Islamabad over Pakistan's plan to fence and mine sections of the long, mountainous frontier.

The joint coalition and Afghan forces battled Taliban fighters for seven hours after they were ambushed while patrolling Wednesday in the volatile Sangin district of Helmand province, a coalition statement said.

Acting on an intelligence report of militant activity in the area, coalition forces then called in an airstrike, the statement said. The battle left 24 militants dead, while two coalition soldiers suffered minor injuries, it said.

NATO and Afghan troops launched their largest-ever offensive last month in southern Afghanistan to flush out Taliban militants from part of opium-producing Helmand province. Scores of militants have been killed in a campaign supposed to open the way for economic development and persuade Afghans to support the feeble government of President Hamid Karzai. "We threw the first punch, and it was a good one," said U.S. Gen. Dan McNeill, commander of NATO's International Security Assistance Force. "We will continue to keep our hands up, hooking and jabbing and trying to dictate the terms."

However, the effort has been marred by a mounting number of civilian casualties caused by international forces, as well as militants.

A NATO soldier shot at a vehicle in eastern Khost province on Thursday, killing a 12-year-old girl and wounding a 2-year-old, said provincial police chief Mohammad Ayub.

NATO said the soldier opened fire after a vehicle moved around a line of waiting cars at a checkpoint and ignored verbal warnings and hand signals to stop.

"They (NATO troops) fired on the vehicle because they thought it might have explosives," Ayub said.

In other violence, U.S. special forces and Afghan troops clashed with insurgents disguised as police officers in western Herat province, the coalition said.

The militants, wearing fake police uniforms, opened fire on the troops as they approached an illegal checkpoint on Wednesday, the coalition said in a statement. It said the patrol returned fire, killing three militants and wounding three others.

The Afghan Defense Ministry said its troops were fired on by Pakistani forces as they tried to remove a fence near Bermal, a notorious hotspot for Taliban operations in Afghanistan's Paktika province. Afghan troops returned fire, it said.

A senior Pakistani military official confirmed that Pakistani troops fired warning shots at Afghan soldiers who tried to enter Pakistan from the Bermal area. But the official, who spoke on condition of anonymity because of the sensitivity of the information, denied that any part of the fence had been removed.

Under pressure from the United States to prevent attacks in Afghanistan, Pakistan is fencing what it says are selected insurgent infiltration routes in order to reinforce the efforts of tens of thousands of troops deployed along the border.

Afghan President Hamid Karzai has dismissed the fence as a distraction from the issue of militant safe havens on Pakistani soil, and says the barriers will only hamper civilians crossing legitimately. ___ Associated Press writers Fisnik Abrashi and Amir Shah in Kabul and Munir Ahmad in Islamabad, Pakistan, contributed to this report