Tracking down Osama bin Laden has proven tougher than getting to Abu Musab al-Zarqawi because the top al-Qaida leader does almost nothing to call attention to himself and is protected by a ring of far more faithful followers, intelligence experts said Thursday.

The mastermind of the Sept. 11 attacks avoids using satellite phones and the Internet. He is likely holed up along the Pakistani-Afghan border in rugged, remote terrain, protected by loyal tribesmen.

Al-Zarqawi was killed Wednesday just 30 miles from the Iraqi capital. In late April, he was featured in a videotape firing a machine gun in the desert and talking to insurgents.

"Osama bin Laden is a far more difficult leader of al-Qaida to be caught as compared to al-Zarqawi," said Talat Masood, a retired Pakistan army general. "Firstly, bin Laden is not involved in day-to-day operations and we believe that he enjoys the support of much more loyal people."

Al-Zarqawi had a $25 million bounty on his head, the same amount offered by the United States for information leading to bin Laden.

Henry Crumpton, the U.S. ambassador in charge of counterterrorism, last month called parts of Pakistan's border region a "safe haven" for militants. He said bin Laden was more likely to be hiding there than in Afghanistan.

According to a senior Pakistani security official, bin Laden avoids using the Internet or satellite phones.

Bin Laden "has seen the fate of those who used satellite phones. He has seen that many such people were arrested by us, and they included some close associates of the al-Qaida chief," the official said. He spoke on condition of anonymity because of the sensitive nature of his job.

The official said Pakistani forces, in cooperation with U.S.-led coalition troops in Afghanistan, were working to get closer to bin Laden, but "so far we don't have any clue on his whereabouts."

The Afghan Defense Ministry spokesman, Gen. Zahir Azimi, said he hopes al-Zarqawi's death will kick start the hunt for bin Laden. "The hunt for Osama continues," he said.

More than 20,000 U.S.-led coalition soldiers are deployed in Afghanistan pursuing Taliban and al-Qaida fighters. Pakistan has 80,000 soldiers in its Waziristan tribal region, the area regarded as the most likely hiding place for bin Laden and his top deputy, Ayman al-Zawahri.

The two leaders are now fairly disconnected from al-Qaida's activities, said a senior Western diplomat in Islamabad, who agreed to discuss the matter only if not quoted by name because of the sensitive topic.

"They've been able to escape detection as they aren't communicating and aren't effectively involved in al-Qaida operations. It makes it very hard to run them down, but moves them significantly from an operational role to a symbolic one," he said.

"It doesn't make any sense to talk of getting closer to them. One day they will be killed or captured, and it will happen like that," the diplomat said, snapping his fingers.