KANDAHAR, Afghanistan - The battle has been joined in the eastern mountains. But across the daunting Afghan landscape, the hunt for the No. 2 target in America's anti-terror war is going on far from Operation Anaconda.

Mullah Mohammed Omar remains a tantalizing quarry, always just beyond reach. Osama bin Laden, the top fugitive and longtime "guest" of Omar's Taliban regime, seems to have vanished.

"The Americans are very busy, trying very hard, working day and night" in search of Omar, said Ahmed Wali Karzai, a key official in the Kandahar region and brother of Afghanistan's interim leader.

In the Anaconda fighting, 300 miles northeast of here, U.S.-led forces are believed to have hundreds of fighters trapped - both Arabs and others from bin Laden's al-Qaida group and Afghans from Omar's deposed regime - in a grinding offensive in Paktia province's wintry mountains.

Capturing some top commanders, even the one-eyed Taliban leader Omar, would make the operation a major success. But there's no word that Omar or bin Laden are caught in that Paktia encirclement, and so the search goes on elsewhere, from such places as a gritty mountain town north of here, and in the rock-strewn desert to the west - each a potential zone for a new military operation.

The latest credible reports, reaching southern regional Afghan officials last month, said Omar had been sighted in Uruzgan province, among the 10,000 foot peaks of the Baba Range, the razor-edged "papa" mountains of Afghanistan 90 miles and more north of here.

"That came from two or three sources, not related to each other, and so that could be credible," said Kandahar government spokesman Yusuf Pashtun.

In fact, secretive U.S. special operations teams recently were seen working out of a government building in Tarin Kot, the remote Uruzgan provincial center seven hours north of here over broken, muddy mountain roads.

Other American operatives were bunked down early this week in the sandblown Hotel Bust, in the ramshackle, mud-walled town of Lashkar Gah, the main center of Helmand, the desert province west of Kandahar.

"They're patrolling out around the province, searching for al-Qaida and Taliban leaders," the governor's top deputy, Haji Pir Mohammad, told The Associated Press. "They haven't found any yet, but they are interrogating people everywhere."

Helmand, an old Taliban stronghold, is of special interest because early reports put Omar in the mountain hamlet of Baghran in the province's far north, where it borders Uruzgan. More recently, the Afghan interior minister, Yunus Qanooni, said he had information Omar was under the protection of tribesmen in southern Helmand, a vast wasteland dotted with hot springs and tiny settlements.

Intelligence gathered by U.S., British and other teams in Uruzgan, Helmand and elsewhere could set the stage for further military operations, though perhaps not on the scale of Anaconda, which was mounted against the largest detected remnants of al-Qaida.

In Omar and his protectors, however, the Americans face canny and capable opponents on their own territory, guerrilla veterans of Afghanistan's endless wars.

"They've been around for 20 years. They know how to get away and hide," said Karzai, a member of the southern region's military council. "And they have Arabs with them who know everything about the Americans - not to use their satellite phones and other equipment, for example."

The terrain itself can defeat modern technology. "You can't even drive there," Karzai said of the Uruzgan areas where Mullah Omar has been reported spotted.

Omar, spiritual leader of the Taliban movement, got away on the night of Dec. 6 with trusted aides as part of a deal surrendering this Taliban stronghold city to anti-Taliban forces. The capture of Kandahar marked the collapse of the 5-year-old radical Islamic regime.

The Afghan warlord who brokered that deal - which was never sanctioned by the Americans - sounded sure at the time that Omar would fade, untouched, into the Afghan landscape.

"No one will catch him," Mullah Naqibullah said then.

These days Naqibullah, also a member of the regional military council, is less outspoken, but sounds no less certain. "I really don't know where he is. But Afghanistan is full of mountains," he told a reporter. "Hundreds of mountains."

In the end, the leads to Omar may come not from surveillance satellites or mud hut-to-mud hut canvassing, but from Omar's own colleagues.

About a dozen senior ex-Taliban officials, in hiding in neighboring Pakistan, have been quietly negotiating for weeks to surrender and face investigation of their harsh years in power. When they come in from the cold, Afghan and U.S. officials hope, they may bring with them some hard information that finally would bring their supreme leader within reach.