Usama bin Laden's (search) deputy, Ayman al-Zawahri (search), may be cornered by Pakistani forces and possibly wounded, in a major battle near the Afghan border. An air strike was being launched Friday to flush out the resistance.
Pakistan President Gen. Pervez Musharraf (search) said a "high value" target was believed trapped in South Waziristan, a semi-autonamous tribal belt that has resisted outside intervention for centuries.
Hundreds of troops and paramilitary rangers pounded several fortress-like mud-brick compounds with artillery and fired on them from helicopter gunships. Entrenched suspects continued to resist.
An intelligence official said "dozens" were killed Thursday. At least 41 people — 15 soldiers and 26 suspected militants — were killed earlier this week in fighting in the area.
The officials told The Associated Press that intelligence indicated the forces had surrounded the Egyptian-born al-Zawahri in an operation that began Tuesday, the first major break in the world's most intense manhunt in more than a year.
The region has long been considered the most likely hiding place for the top two Al Qaeda (search) leaders — but there was no indication bin Laden was with al-Zawahri. However, the two have traveled together in the past, and bin Laden and al-Zawahri appeared jointly in video tapes released shortly after the Sept. 11, 2001, attacks on the United States.
The United States has offered a $25 million reward for information leading to al-Zawahri's capture. On Thursday, the U.S. House of Representatives doubled the reward for bin Laden's capture to $50 million.
"We have been receiving intelligence and information from our agents who are working in the tribal areas that al-Zawahri could be among the people hiding there," a Pakistani military official said. "All of our efforts are to capture him."
An intelligence official and a senior politician in Musharraf's government both confirmed the account. All spoke on condition of anonymity.
The intelligence official said information was also coming from some of the 18 suspects captured during Thursday's operation. Some said during interrogation that al-Zawahri was wounded in the raid, the official said.
A senior counterterrorism official told Fox News it is believed to be al-Zawahri because of "multiple specific pieces of intelligence" gathered.
Pakistani journalist Hamid Mir said the Pakistani military has "already sent some choppers to that area. They will strike all those bunkers from where the Al Qaeda fighters are fighting against Pakistani forces."
Maj. Gen. Shaukat Sultan (search), spokesman for the Pakistani military told Fox News the reports that the cornered individual is al-Zawahri are purely speculative, but confirmed that "the militants are very well dug in" and the resistance is "unusually strong."
"This is not a small area," he said. "The area has been effectively surrounded by the troops and we are making all the effort to ensure people do not slip out during the night."
Responding to reports a military strike was in the works, Sultan said: "We have all kind of support lined up ... if required, it is going to be used."
"We would make all the effort to cap people alive, if not, effort would be made to flush them out whether alive or dead."
'He's a Whale'
White House Communications Director Dan Bartlett (search) told Fox News there is no confirmation as to who is cornered, but if it is al-Zawahri "it would be a significant victory in the war on terror. When you're talking about big fish, he's a whale."
Mansoor Ijaz, Fox News' foreign affairs analyst, said capturing al-Zawahri would be "bigger than Usama bin Laden" because of his mastery in planning and coordinating deadly terrorist attacks and ability to link Al Qaeda cells around the world.
Musharraf said in a televised interview that he'd spoken with the commander of Pakistani troops in the region. He said the commander reported "fierce resistance" from a group of fighters entrenched in fortress-like buildings, and that there were indications a senior figure was surrounded.
"He's reasonably sure there's a high-value target there," Musharraf said. "They are not coming out in spite of the fact that we pounded them with artillery."
Powell Praises Pakistan for Terror War Help
The news came the same day as Secretary of State Colin Powell (search ) announced in the capital, Islamabad, that Washington was bestowing the status of "major non-NATO ally" on Pakistan, and praised the country for its help in the war on terror.
National security adviser Condoleezza Rice said in a televised interview she could not confirm the reports.
But, she said, if al-Zawahri were captured, "it would be of course a major step forward in the war on terrorism, because he's obviously an extremely important figure. But I think we have to be careful not to assume that getting one Al Qaeda leader is going to break up the organization."
White House spokesman Scott McClellan said that the Pakistanis "believe there is a high-value Al Qaeda target possibly involved" in the operation. He said he had no information on who the target was. He said Bush was informed of the search.
The 52-year-old former Egyptian surgeon is believed to be the brains behind the terror network, with bin Laden serving more as spiritual leader and financial backer.
Often seen by bin Laden's side in videos released to Arab television networks, the doctor was also thought to serve as Al Qaeda leader's personal physician.
Al-Zawahri's Egyptian Islamic Jihad was believed behind the assassination of President Anwar Sadat during a Cairo military parade in 1981. He merged the organization with Al Qaeda in 1998.
Al-Zawahri has continued to spread his message since the Sept. 11 attacks in audiotapes, the latest broadcast on Feb. 24, in which he taunted President Bush and threatened more attacks on the United States. Another tape criticized France's decision to ban Islamic headscarves in schools.
Under pressure from Washington, Pakistan has arrested more than 500 Al Qaeda suspects and has turned most over to the United States. The last major capture was that of Khalid Shaikh Mohammed, the former Al Qaeda No. 3, who was nabbed on March 1, 2003, in a house near the capital and quickly delivered to U.S. custody. He is being held at an undisclosed location.
Pakistan Military Pursues Tribal Leaders
The Pakistani military has been pursuing 100 tribal leaders whom authorities want to roll into their efforts to hunt Al Qaeda in the Waziristan frontier. So far, about two-thirds have said they would provide information and turn over any Islamic militants in their territories, American defense officials said.
The others face destruction of their homes by the Pakistani military, officials said.
There have been several anti-terror sweeps in the tribal regions in recent months, but none so bloody as the operation that began Tuesday. Pakistani troops have moved 70,000 troops into the border region, and Musharraf on Monday promised to rid the tribal areas of foreign terrorists.
U.S. officials say they are watching to see if the Pakistani actions send militants back into Afghanistan, where U.S. troops operate freely. The U.S. military on Sunday announced the start of a new operation to track down senior Al Qaeda and Taliban fugitives.
Two American soldiers were killed and two others were wounded in fighting Thursday in central Afghanistan, the U.S. military said. At least five attackers were killed in the battle.
The military said that because of the location, the fighting did not appear to be directly related to the siege against al-Zawahri.
Afghan officials told AP they were closely monitoring the Pakistani operation.
"We are hopeful operations being carried out in border regions will yield some desirable results," said Afghan Foreign Ministry spokesman Omar Samad. "If a well known figure is part of these captures ... the world will be a safer place."
Thursday's raid concentrated on three South Waziristan towns — Azam Warsak, Shin Warsak and Kaloosha. Early morning calls from mosques warned residents to leave the area, apparently to give the troops more room to operate.
Powell, who left the country hours before the news broke, also said he believed there was evidence that bin Laden is hiding in the rugged border area.
"No one has seen him, so how can one be sure?" Powell told Geo TV. "But he has certainly given evidence that he is alive and active. But we can't be sure.
"And if he is alive and active, and the evidence suggests that he is, and if he is in the area of the Pakistan-Afghan border, that's a very difficult area to find someone who doesn't want to be found."
The Associated Press contributed to this report.