U.S. artillery and airstrikes killed between 50 and 60 suspected Taliban militants on Tuesday, the fourth day of a NATO-led offensive in southern Afghanistan, a NATO spokesman said.

The U.S. troops, operating under NATO command, clashed with the militants in Panjwayi district of Kandahar province, where an offensive began over the weekend to flush out hundreds of Taliban fighters who remained trapped and unable to flee. NATO has already reported more than 200 Taliban killed in the operation.

Maj. Quentin Innis, a NATO spokesman, said the troops had identified Taliban positions and the two sides had exchanged fire. He said the estimate of 50 to 60 killed in Tuesday's fighting was based on reports from troops looking through "weapons sights and other observation devices."

He said there had been no NATO or Afghan troop casualties.

It wasn't possible for reporters to reach the site of the battle to independently confirm the death toll.

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A Panjwayi district council member, Haji Agha Lalai, said bombings by NATO warplanes have killed 21 civilians over the past three days in an area called Zungawad. NATO spokesman Maj. Scott Lundy said he had no immediate details to support Lalai's claims.

The Afghan Defense Ministry on Tuesday said 200 militants have died since Saturday -- increasing its previously reported toll of 89. The dead included four Taliban commanders and 12 of their bodyguards, a ministry statement said, citing intelligence reports. No further details were available.

Five Canadian soldiers have also been killed, one in "friendly fire" by a U.S. warplane Monday.

Mullah Dadullah, the Taliban military commander for south and southeastern Afghanistan, on Monday rejected NATO's claim of over 200 dead.

Qari Yousaf Ahmadi, who claims to speak for the Taliban, said Tuesday that if NATO had killed so many Taliban fighters, they should show them to the media. He also denied that hundreds of militants were trapped in Panjwayi, and said its fighters were giving a hard time to NATO and Afghan forces there. He spoke to an Associated Press reporter by phone from an undisclosed location.

Lundy, the NATO spokesman, said earlier Tuesday that an estimated 700 militants were "trapped" in an area spanning several hundred square kilometers (miles) in Panjwayi and Zhari districts, some in fortified compounds, others moving in the open.

NATO has also reported that 80 Taliban have been arrested and a further 180 have fled the fighting -- some of the most intense since the fall of the Taliban regime nearly five years ago.

"It's a complex battle space. Some (Taliban) elements are fixed, others are moving," Lundy said.

During Monday's clashes, a U.S. A-10 Thunderbolt warplane supporting NATO mistakenly strafed Canadian troops fighting Taliban forces in Panjwayi, killing one soldier and seriously wounding five.

A top U.S. general expressed sadness over the incident, which is being investigated by a board of military officers.

"The death or injury of each and every coalition member is a tragedy that saddens us, our families and the military and civilian members of the coalition," Lt. Gen. Gary North, commander of U.S. Central Command Air Forces, said in a statement.

A 12-year-old girl died and nine other civilians have been treated for injuries from the fighting in Panjwayi at a Kandahar hospital since Sunday, said Dr. Qayyum Pohya, the hospital's chief. Seven of the civilians have been discharged and the two others were in stable condition.

The bloody contest between resurgent Taliban militants and U.S. and NATO forces has left hundreds dead in each of the past four months -- the deadliest spate of violence since the pro-Al Qaeda Taliban regime's 2001 ouster.

The latest clashes came as NATO leaders, including Secretary General Jaap de Hoop Scheffer and top commander U.S. Gen. James L. Jones, were in Afghanistan for talks with Afghan officials on a security and development accord and to assess progress in the alliance's mission to stabilize the volatile south.

The NATO chiefs, who arrived in Afghanistan late Monday, are due to travel around the country and on Wednesday meet beleaguered President Hamid Karzai. Their three-day visit will coincide with a trip to Kabul by neighboring Pakistan's President Gen. Pervez Musharraf.

Pakistan, a key Western ally in the war on terrorism, is under increasing pressure to crack down on Taliban on its soil. Afghanistan claims militia leaders stay in Pakistan and that militants launch cross-border attacks. Pakistan denies the presence of Taliban leaders and says it has 80,000 troops at the border to stop infiltration.

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