Fugitive Taliban chief Mullah Omar pledged to drive foreign troops out of Afghanistan in a statement released Friday, as NATO and Afghan forces killed more than 12 of his fighters in the volatile south.

The purported message from Omar, the authenticity of which could not be immediately confirmed, urged the Taliban to "sacrifice" their lives and "never submit or accept defeat."

"I am confident that blood of innocent people and mujahedeen will yield results," said the statement, timed for the Muslim religious festival of Eid al-Adha. "The enemy will have to quit the region with humiliation and disgrace."

"Afghans have a history of expelling their enemies as no enemy and invader has quit Afghanistan willingly," it said.

The message, sent in Pashto language with an accompanying English translation, was received by The Associated Press in Pakistan in an e-mail from Taliban spokesman Mohammed Hanif.

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Statements from the Taliban leader — whose whereabouts are a mystery — are periodically issued through Hanif, who claims to speak for the hardline militia.

The latest message comes amid stepped-up attacks this year by the Taliban, particularly in southern Afghanistan, where they have been waging fierce battles with Western and Afghan forces.

About 4,000 people, mostly militants, have died in 2006, the bloodiest period in Afghanistan since the fall of the Taliban regime in late 2001.

Suspected Taliban militants attacked a police post late Thursday using machine guns and rocket-propelled grenades, said Khost provincial police commander Mohammad Ayub. The ensuing battle lasted more than an hour.

NATO forces called in a helicopter to attack the Taliban, Ayub said, adding that after the clash ended, the bodies of more than 10 militants were recovered.

NATO spokesman Maj. Dominic Whyte said there were no injuries among NATO troops. Ayub said there were also no casualties among Afghan forces.

Also Thursday, suspected Taliban militants attacked a police checkpoint in southern Helmand province, said provincial police chief Ghulam Nabi Malakhail. Police returned fire and two Taliban were killed in a 20-minute gun battle, he said. No police were injured.

In the statement, the Taliban leader accused foreign forces of "ruthless bombing" that had killed and displaced thousands of Afghans including women and children.

"It has now become a permanent cruel practice and barbaric habit of our enemy. We must stand by the people to fight against the enemy and to take revenge of their blood," it said.

Hundreds of civilians have died in this year's fighting, some in U.S. and NATO bombing of suspected Taliban hide-outs, others caught in Taliban suicide attacks.

Omar went into hiding after a U.S.-led invasion toppled his Taliban regime in Afghanistan five years ago. Afghan officials say he is hiding in the Pakistani city of Quetta, while Pakistan says he is in Afghanistan.

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