PESHAWAR, March 19: Paramilitary forces, supported by regular troops, began a house-to-house search in Shin Warsak on Friday, the second day of a massive operation launched against foreign militants in the South Waziristan tribal region.

The number of casualties among the militants holed up in the area could not be known but officials said it could be 'very high' given the intensity of the shelling and rocket-firing by Cobra helicopter gunships.

Officials told Dawn the paramilitary forces and regular troops from the Pakistan Army used artillery and helicopter gunships as they launched the search for foreign militants in Shin Warsak - a village of about 300 households - at around 2.45pm.

The troops operated in about 30sq-km of area, but concentrated on Shin Warsak, about nine kilometres west of regional headquarters Wana, where officials had earlier said they thought a senior Al Qaeda figure had been cornered and wounded.

President Gen Pervez Musharraf told a US television news channel on Thursday about the likely presence of what he described as a high-value target in the area. He did not identify the person nor specified the area.

But officials familiar with the operation said the military operating in the area thought the 'high-value target' could be Osama bin Laden's lieutenant Dr Ayman Al Zawahiri.

A senior official said that speculations about the likely presence of a senior Al Qaeda leader were based on a report by an informer that 'an important man' wounded in the Tuesday's encounter with paramilitary forces had first moved to place 'A' and then to place 'B'.

"Now who this important man could be is anybody's guess," the official said. The 'important man', he said, was possibly wounded when his bullet-proof double-cabin pick-up truck had rammed into a mud wall after coming under intense fire from paramilitary forces.

The officials said the search operation had been launched on the outer perimeter of Shin Warsak. "There has been very little progress on the ground," said one official.

"It would take a couple of days to complete the search in just one area," said another official. He said that troops had found bodies of two Arabs with a wireless set during the search.

But Fata's secretary for security, Brig Mahmood Shah, told Dawn that troops were taking extreme caution to avoid being ambushed or hit by remote-controlled or other explosive devices.

"They are still holding their positions," Brig Shah said. "Firing from their side in Shin Warsak was a little subdued but the resistance has stiffened in the adjoining Kaloosha village," he said.

It was possible, he said, that the militants were trying to save ammunition for a final assault. "They have a lot of ammunition," he added. The official said that the forces which had thrown a security cordon around the entire stretch of the operation used effective fire-power to preempt any attempts by militants to get away.

Brig Shah said the army had thwarted several attempts by militants to get away. Sources said that two Chechens identified as Danyar and Qurban Ata were commanding about 500 to 600 foreign militants holed up in the area and were coordinating their attacks through wirelesses.

Sources estimated that the number of local fighters holed up with militants could be less than 100. Foreign militants included Uzbeks Afghans and Arabs and some Chinese Uighurs from the Xinkiang autonomous region.

Sources said that Tahir Yaldashev alias Qari Tahir, who had taken over the IMU following the death of Jumma Namangani in an aerial attack by the US-led coalition, could also be among the militants holed up in the area.

They said that the Special Operation Task Force had conducted the Wana-2 operation in Kaloosha on Feb 2 following specific intelligence reports about his presence in that area.

He said that some foreign militants believed to be Chechens were also holding out in Kuth Kalli near Karikot. Residents in Wana said that the intensity of firing had died down towards the afternoon although the roar of rockets fired from helicopter gunships reverberated in the area.

An official confirmed that helicopters had taken part in the military action on Friday and said that the army might also press fighter jets into action on Saturday to 'finish off the business'.