In what is turning out to be the army's most disastrous operation in its two-year al-Qaida hunt, a security official revealed on Friday that a total of 37 army and paramilitary troops had been killed in battle since the operation began on 16 March.

That figure includes 16 troops killed on the first day when they were surprised by scores of heavily armed fighters, apparently protecting an unidentified foreigner escaping in a bullet-proof vehicle.

In another disastrous raid, 14 army troops were slaughtered in one hit on 18 March when they mistakenly landed by helicopter in a nest of battle-hardened fighters, holed up in two tribal villages near the Afghan border.

"A contingent led by a major mistakenly landed in a militants' den and was virtually butchered," the security official, who could not be identified told French news agency AFP.

Another seven soldiers were killed in later days of the operation.

Separate attacks

"The use of force should be the last resort. I would like political process to lead the way. I firmly believe that even in worst case scenarios negotiations are the best way to resolve issues."

Lieutenant General Safdar Hussain

"The military's death toll in the battle field is 37," the official said.

Outside the theatre of operation, three separate attacks by unknown assailants on army bases and an army convoy have left 17 soldiers dead.

Twelve paramilitaries have been missing since the botched 16 March raid, and eight army troops have disappeared since 18 March, bringing the total missing troops to 20.

Authorities believe they have been taken hostage by Yargulkhel tribesmen at the centre of the fighting. Efforts so far by tribal elders to persuade them to surrender their hostage have failed.

Two administration officials are also believed to have been taken hostage.

Up to 55 foreign and local fighters had been killed in the military offensive, Interior Minister Faisal Salah Hayat told the parliament on Thursday.

Many arrests

Around 163 suspects had been arrested during the operation, chief of security for the tribal areas Brigadier Mahmud Shah said on Thursday night.

However some 60 have been released, the security official who could not be named said.

"Now we have little more than 100 with us. The majority of them are Afghans and there are few Chechens and Uzbeks as well," he said.

About 140 people have been
arrested by Pakistani authorities

"Members of the Yargulkhel tribe have refused to negotiate until troops vacate," said Mohabbat Khan Shirani, one of nine elders sent to negotiate with the hostage-holders on Thursday night.

Tribesmen from the Yargulkhel clan, a fiercely independent Pashtun sub-tribe, have been fighting alongside hundreds of al-Qaida-linked fighters against Pakistani forces since 16 March in a rugged tribal area of South Waziristan, near the Afghan border.

No progress

Tribal elders have been trying to persuade the fighters to hand over the al-Qaida suspects, tribal chiefs wanted for harbouring the fighters, and 14 hostages.

They have so far made no head way.

Meanwhile, Aljazeera broadcast a message on Thursday purportedly from al-Qaida deputy leader Ayman al-Zawahiri calling on Pakistanis to overthrow President Pervez Musharraf.

Pakistani officials had initially suggested that the fighters in South Waziristan were protecting a senior al-Qaida leader, possibly al-Zawahiri, but they have backed off those claims in recent days.

"After conducting a technical analysis, the CIA has assessed that the voice on the tape that was aired yesterday on Aljazeera television is likely that of Ayman al-Zawahri. It is not clear when the tape was recorded"

CIA official

Nobody ever saw al-Zawahiri, and regional experts believe the high value target was instead probably an Uzbek or Chechen leader who may have escaped.

Pakistan scoffs threat

Pakistan's military dismissed as "absolutely ridiculous" the taped message, and vowed to step up the hunt or al-Qaida on its Afghan border.

President Pervez Musharraf's government said more troops would be sent to its semi-autonomous tribal territories bordering eastern Afghanistan to reinforce a bloody campaign to flush out fighters of the al-Qaeda network and other fighters.

The 11-day operation sparked a defiant message purportedly by bin Ladin's right-hand man, Ayman al-Zawahri, describing the Pakistani leader as a "traitor" to Islam.

Major-General Shaukat Sultan, a military spokesman, scoffed at the threat. "It's absolutely ridiculous," he said.

The CIA said on Friday that the message aired this week was "likely" the voice of al-Zawahri, who Pakistani forces recently had believed they had trapped in a battle on the border region.

"After conducting a technical analysis, the CIA has assessed that the voice on the tape that was aired yesterday on Aljazeera television is likely that of Ayman al-Zawahri. It is not clear when the tape was recorded," the CIA official said.

Islamist parties held nation-wide
protests against the al-Qaida hunt

The message also calls on Pakistanis to support the al-Qaeda network.

The military commander in charge of the Wana operation told a local newspaper he wanted to wind up the operation by Saturday to allow a political rather than military solution.

"We are winding up the operation by Saturday," Lieutenant General Safdar Hussain said in an interview with the Dawn newspaper.

'Last resort'

"The use of force should be the last resort. I would like political process to lead the way. I firmly believe that even in worst case scenarios negotiations are the best way to resolve issues."

"The best option ... now is [for the fighters] to lay down their arms and surrender and not create a situation where the army is forced to be employed as an instrument of power."

Hussain said the mission of "destroying and denying sanctuary to militants" had been accomplished.

Some 140 people have been arrested.

A regional security commander said this week that many of the fighters, including the high value target, had escaped.