KABUL, Afghanistan (AP) – A surge of fighting in Afghanistan’s restive south killed 64 insurgents and 10 Afghan security men, the worst single loss suffered by the American-trained government army, U.S. and Afghan officials said Thursday.

The U.S. military said the bloodshed in Kandahar and Zabul provinces was as much the result of operations by government forces and the 18,000 soldiers of a U.S.-led international coalition as from a resurgence by Taliban loyalists and other insurgents.

“We’re going out and aggressively looking for them,” said a U.S. spokeswoman, Lt. Cindy Moore. “It’s unfortunate that so many Afghan army troops were lost.”

Moore said nine Afghan soldiers died in a firefight that erupted when rebels ambushed an Afghan army patrol near Spin Ghar in Kandahar late Wednesday, but she said 20 insurgents were killed after U.S. warplanes joined the battle.

The Afghan Defense Ministry said the nine army deaths were the worst ever for the force that has been put together with U.S. and other foreign assistance since the hard-line Taliban regime was toppled in late 2001.

Three Afghan soldiers and an American soldier attached to the unit were wounded, while six militants were captured, Moore said.

The clash came after American soldiers and insurgents waged the country’s deadliest fight in nine months, battling Tuesday and Wednesday in Zabul, another province along the Pakistani border that has seen more insurgent activity since a winter lull.

The U.S. military said 44 rebels died in that fighting, which also killed an Afghan police officer and wounded six U.S. soldiers and five Afghan policemen. On Wednesday, the U.S. command had reported 21 insurgent deaths, but it said troops found more bodies.

The insurgents were a “mix of Taliban and anti-coalition militants,” a U.S. spokesman, Col. James Yonts, told The Associated Press. “These were well-trained, well-armed people … not just a rogue group. They didn’t flee. They stood and fought.”

A spokesman for the governor of Zabul, Ali Khail, told the AP that documents found on the dead militants in the mountains of Dehchopan district showed two were Chechens and one was Pakistani. He would not describe what was in the documents.

U.S. officials declined to discuss the dead fighters’ nationalities.

The death toll in the Zabul fighting was the heaviest since Aug. 2, when Afghan troops and U.S. warplanes killed up to 70 militants in a daylong battle in the southeastern province of Khost.

Afghanistan’s interior minister, Ali Ahmad Jalali, said at a news conference that more than 100 militants and at least 12 Afghan policemen had been killed over the past month, but his figures didn’t include all the latest deaths. Several civilians, a U.S. soldier and a Romanian soldier also have been killed.

Jalali also announced a possible breakthrough in the kidnapping of three U.N. election workers in October, an abduction ahead of the presidential vote that intensified worries among the 3,000 foreigners working in Afghanistan.

He said six men in police custody had confessed and described how they planned the kidnapping of the three, who were released unharmed after a month.

A Taliban splinter group had claimed responsibility for the abduction, but officials and diplomats suggested that criminals – possibly working for factions opposed to President Hamid Karzai’s U.S.-backed government – were responsible.