Taliban militants in northwestern Pakistan have ambushed a military convoy, killing six soldiers.  Hours earlier, army helicopters and warplanes pounded suspected militant hideouts in the region, where leaders of the Pakistani Taliban, Baituallah Mehsud, is believed to be running terror camps. 

Pakistani officials say heavily armed Taliban fighters ambushed a military convoy of several vehicles in the North Waziristan border region.  The attack instantly killed several soldiers and the two sides exchanged fire for some time.  But there are no details whether militants suffered losses.

The ambush took place hours after Pakistani aircraft and helicopter-gunship bombed two Taliban compounds in the neighboring South Waziristan tribal region.  The air raids are said to have killed an unknown number of militants, but independent verification of these reports is not possible because of the remoteness of the rugged region that borders Afghanistan.

Pakistani authorities say the military strikes are part of the campaign to neutralize a militant threat before a major air and ground offensive is launched to eliminate Baituallah Mehsud, the fugitive commander of the Pakistani Taliban militants.

In another move to corner the militant leader and his top commanders, the Pakistani government published an announcement in leading newspapers offering a reward of more than $600,000 for information leading to Mehsud's capture or death.  More than $900,000 are also offered for 10 of his allies.

The United States has already announced a $5-million reward for Mehsud.  He is accused of harboring the al-Qaida network, whose fugitive leader Osama bin Laden is believed to be hiding in the mountainous Pakistani region.

Critics like Mehmood Shah, a former security chief for the volatile Pakistani border region, say the policy of offering bounties has not worked.  But he says the move is a strong indication the Pakistani government is making every effort to eliminate the terrorist forces.

"There is huge [head] money for Osama Bin Laden and it has not materialized," Shah said.  "So I am sure it is just conveying a message.  But the main thing would be the operation by the military, which should be conducted with lot of care and lot of determination."

The Pakistani military has won appreciation both at home and abroad, particularly from the United States for its ongoing anti-Taliban offensive in the northwestern Swat and neighboring districts.

Top officials claim the successful military operation has killed more than 1,600 militants and is nearing its end.  But the government is also under fire for failing to kill or capture top Taliban leadership in the area.

The offensive began in late April and is said to have killed most of the militants.  But it has also forced hundreds of thousands of civilians to flee the region and take refuge in other parts of Pakistan.

Taliban militants have responded to the offensive with suicide bombings in towns and cities and attacks on the military across the country, killing scores of people.

The latest violence occurs as the top U.S. commander for the region, General David Petraeus, arrived in Pakistan for talks with Pakistani officials.