"Two days ago, six Afghan National Army (ANA) companies numbering about 1,000 soldiers departed for the Zermat valley region in the southern Paktia province," US Colonel Rodney Davis told reporters at the Afghan army's Pul-i-Charki barracks 15 kilometres (10 miles) east of Kabul.

"Operation Warrior Sweep marks the ANA's first major combat operation and Operation Warrior Sweep is ongoing.

"The ANA's mission is to kill, capture and deny sanctuary to anti-coalition fighters and to disrupt anti-coalition activity in the Zermat valley region in support of the Islamic transitional government of Afghanistan," he said.

Davis was referring to Taliban remnants and their al-Qaeda allies and fighters of renegade former premier Gulbuddin Hekmatyar, who regularly launch attacks on foreign and government targets.

The Zermat valley region, 100 kilometres (60 miles) south of Kabul, was the scene of the massive Operation Anaconda assault against al-Qaeda and Taliban fighters in March last year.

Coalition forces last month launched two operations against suspected Taliban and al-Qaeda fighters in the area.

Operation Warrior Sweep was intended to disrupt routes used by these anti-coalition forces in the mountainous Afghan-Pakistan border area.

The operation had been "planned for some time and it is not in direct response to anything that would have occurred yesterday or the day before yesterday or in the recent past," the colonel said.

"ANA combat operations complemented by coalition security operations are designed to disrupt the anti-coalition network and advance security and stability within the region," he said.

"The ANA will establish a long-term presence in the Zermat valley region and I'm very pleased to announce that from this point on, the ANA will be a key contributor to Afghanistan's security."

Davis said the nascent national army now numbered 5,000 troops, against a forecast eventual strength of 70,000. The United States is leading efforts to train and rebuild the national force, a task the former commander of US-led coalition forces Lieutenant General Dan McNeill described as a "tough road" due to ingrained ethnic and regional suspicions and tensions.

"The Afghan National Army is now 5,000 soldiers strong. They are a trained, disciplined fighting force capable of conducting both combat and civil military affairs operations in conjunction with coalition forces," Davis said.

Afghan infantry troops were backed by US-led coalition forces but Davis would not disclose further details of the ongoing operation or whether any fighting had occurred.

Pakistan had been informed of the operation taking place near its border, he said.

"As a matter of practice we coordinate our activities with the affected governments, so you can be assured that any government affected by this operation has been informed that the operation was launched and is currently ongoing."

Davis said Taliban and al-Qaeda fighters were located in Afghanistan and Pakistan.

"There are anti-coalition forces located in Afghanistan, there are some anti-coalition forces located in Pakistan," he said.

The US-led coalition force of some 11,500 troops is currently hunting Taliban and al-Qaeda remnants and helping with reconstruction work throughout Afghanistan.

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