Associated Press WriterBAGRAM, Afghanistan (AP) -- U.S. and Canadian troops battled al-Qaida fighters in the Shah-e-Kot area Thursday, killing three of them in a 90-minute gunbattle, according to Canadian reporters accompanying the troops.

The Canadian Press news agency quoted U.S. First Lt. Greg Darling of Warren Center, Penn., as saying coalition troops subdued the enemy with anti-tank weapons, heavy machine guns and small arms fire.

There were no U.S. or Canadian casualties, the agency reported.

The troops were conducting mop-up operations in the Shah-e-Kot area, which was abandoned by al-Qaida forces after heavy U.S. airstrikes. Forensics experts conducted DNA tests to make certain none of the terrorist organization's senior leaders was among the dead.

Neither Osama bin Laden nor Taliban leader Mullah Mohammed Omar was believed to be in the Shah-e-Kot valley March 2 when U.S. forces and their Afghan allies launched the biggest offensive of the 5-month-old war. But some corpses were so badly mangled that Maj. Gen. Frank L. Hagenbeck ordered the tests -- just to be sure.

"Even if it's a long shot that maybe one of these al-Qaida leaders (was there), we want to go through every means we've got available to us to try to positively identify them," said Hagenbeck, the commander of all coalition troops in Afghanistan.

A U.S. officer estimated as many as 500 al-Qaida fighters were killed in the 12-day offensive in eastern Afghanistan. But Afghan troops said they found only 25 bodies in the initial sweep of the area. Others may be buried in caves that collapsed during the bombing.

Among the dead were "second and third tier" al Qaida leaders, though Hagenbeck did not explain what he meant.

Helicopters patrolled the valley looking for anyone who might have slipped through a coalition dragnet, sneaking out on smuggling routes and into neighboring Pakistan.

In Washington, Pentagon spokeswoman Victoria Clarke said Wednesday that fighting had "mostly ended" and that troops were in the "exploitation phase," going cave to cave in search of bodies, weapons and intelligence information.

"We will have a long way to go in Afghanistan," she said.

Canadian forces took the lead in the mop-up work following the battle, with 500 troops landing high in the snowcapped mountains to search for al-Qaida fugitives, including Saif Rahman Mansour, the Taliban leader of the Shah-e-Kot fighters.

"We're right on their backs right now," Hagenbeck said of Rahman and his comrades.

A joint Canadian and American team moved systematically through the area, blasting cave entrances with grenade and machine gun fire to make sure no one was hiding inside.

Canadian officers said they found stacks of rocket-propelled grenades, grenade launchers and stacks of small arms ammunition hidden in the abandoned bunkers.

Most of the dead were non-Afghans, and included Chechens and Uzbeks as well as corpses with Mongol features, Hagenbeck said. U.S. officials said they were holding about 20 prisoners who were being interrogated.

Pentagon officials had repeatedly said the only choice facing the enemy troops was to "surrender or die," although Afghan commanders had been prepared to allow them to leave.

Leading the final assault were Afghan commanders Zia Lodin and Gul Haider, who had floated the idea of a negotiated exit.

"There are some fighters who have escaped -- we think to Pakistan," said Shurkurullah, an Afghan commander who uses only one name.

"As Anaconda unfolded, we saw that the larger concentrations of Taliban and al-Qaida fighters began to disperse," said Vice Admiral Greg Maddison, a Canadian military official speaking in Ottawa. "And the area that we are engaged in is one of the areas where some of the fighters went to."

The number of enemy fighters still in the valley had dropped to "double digits," Hagenbeck said.

U.S. officials had hoped to prevent a repeat of the flight from Tora Bora, the cave complex U.S. troops hammered for weeks in December on suspicion that bin Laden was inside.

Afghan militias from the area conducted most of the ground fighting at Tora Bora, and U.S. authorities said they apparently let many al-Qaida fighters escape to Pakistan.

When Tora Bora was finally overrun, there was no sign of bin Laden.

Fighting died down during the last five days, enabling the United States to withdraw most of the estimated 1,400 troops from the 101st Airborne Division and the 10th Mountain Division who fought in the battle.

The coalition casualty toll stood at eight U.S. special forces troops and three Afghan allied fighters.

Hagenbeck also acknowledged that some civilians were killed in the fighting, though he did not say how many. He blamed the deaths on the al-Qaida fighters, who set up mortar positions between the houses in the hamlets of the Shah-e-Kot Valley.

"It's always tragic when noncombatants are killed in something like this," Hagenbeck said.