U.S. and Afghan forces continued ground and air attacks on Al Qaeda and Taliban fighters early Saturday, although bad weather kept enemy troops in caves, according to a military spokesman in Afghanistan.

The Pentagon described the fighting as "sporadic."

On Friday, U.S. and Afghan forces welcomed troop reinforcements and stepped up ground and air attacks on Al Qaeda fighters fulfilling their vow to fight to the death.

U.S. officers said 500 to 600 renegades — more than the initial estimate of the size of the entire enemy force — have been killed since Operation Anaconda began last Friday.

"I have not seen anyone surrender," said Col. Frank Wiercinski, a brigade commander in the 101st Airborne Division.

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The allied toll remained at eight U.S. servicemen and three Afghans.

Fighting in the southern sector of the 60-square-mile area of operation was intense, Col. Joe Smith, chief of staff of the 10th Mountain Division, said Friday at Bagram air base.

Smith said Al Qaeda forces had suffered "lots" of casualties over the past between Thursday and Friday, but he gave no figure.

In Washington, Defense Secretary Donald H. Rumsfeld said Friday that Al Qaeda was also rushing in reinforcements and supplies.

"We have seen some infiltration of additional fighters in small numbers, traveling in SUV's from the south," Smith said.

Heavy snow blanketed the region's mountain passes, but ground and air operations pressed on, and the rumble of heavy explosions from the battle area could be heard more than 20 miles to the north.

With the fight intensifying, the interim Afghan government rushed in reinforcements, bolstering an Afghan force made up largely of militias recruited by U.S. special forces.

The central government was sending about 1,000 new Afghan fighters to the Gardez area, of whom about 600 had already arrived, said town council member Safih Ullah. They were under the command of Gul Hydar, backed by tanks and other fighting vehicles.

A convoy of 12 to 15 tanks was seen in Logar province Friday heading south from Kabul to Gardez. Another convoy included trucks carrying multiple rocket launchers and other vehicles with soldiers armed with rifles and grenade launchers.

The Pentagon is sending about 200 soldiers from the 101st Airborne Division at Fort Campbell, Ky., equipped with 16 Apache helicopters and four CH-47 Chinook helicopter transports. About 107 members of a Canadian infantry unit are also on the way.

Wiercinski said that seven days into the operation, U.S. troops were no longer seeing large groups of fighters. "They are determined. Whether you would call that martyrdom or whatever, they are still determined in their small pockets," he said.

Smith said documents uncovered during the battle have showed that the besieged Al Qaeda fighters "are highly trained military soldiers."

Documents found by coalition troops conducting cave-to-cave searches have shed light on Al Qaeda's use of heavy weaponry, including mortars, small cannons, rocket-propelled grenades and shoulder-fired anti-aircraft missiles.

Still, Smith said the militants were surprised when the offensive was launched March 1.

"I think they believed that we were going to fight them head on and we hit them in the rear. And even though they knew for seven or eight days that we were going to attack, they just didn't know where or exactly when," he said.

Special forces teams established checkpoints along roads and smuggling routes to try to intercept Al Qaeda fighters trying to slip in from the area along the Pakistani border.

An Afghan commander, Abdul Matin Hasankhiel, said some Al Qaeda sympathizers managed to cross the Pakistani border early in the battle but he thought most had been blocked.

Other Taliban and Al Qaeda supporters were believed responsible for two attacks this week in nearby Khost: a shooting attack on U.S. forces at an airstrip and a bomb blast that destroyed a music and video shop, local official Mohammed Ibrahim said.

Hafeezullah, member of the Surmad town council, said men from his region probably joined to fight with Al Qaeda because of the prestige of the local commander, Saif Rahman, a former Taliban official whose family comes from the area.

Rahman issued a call earlier in the week for jihad, or holy war, against the U.S. campaign and had sworn to fight to the death.

The Associated Press contributed to this report.