By Patricia Wilson

WASHINGTON, March 13 (Reuters) - U.S. President George W. Bush shrugged off uncertainty over Osama bin Laden's fate on Wednesday, saying the Saudi-born militant blamed for the Sept. 11 attacks had been "marginalized" in the terrorism business.

"We shoved him out more and more," Bush told a White House news conference. "He has no place to train his al Qaeda killers anymore."

Despite his vow last year to bring bin Laden to justice "dead or alive" for the hijacked plane attacks on New York and Washington, Bush said he no longer spent much time worrying about what had happened to him.

"Terror is bigger than one person," he told reporters. "He is a person who has now been marginalized. His host government has been destroyed. He's the ultimate parasite who found weakness, exploited it and met his match."

After focusing on bin Laden in the weeks immediately after more than 3,000 people died in hijacked plane attacks, Bush now rarely mentions him by name at all.

"I don't know where he is ... deep in my heart I know the man is on the run if he's alive at all," the president said. "I just don't spend that much time on him to be honest with you."

Bush pointed out that lately he "hadn't heard much" from bin Laden who, in the past, has been seen on videotape and said he did not believe the Saudi exile was "at the center of any command structure."

"I truly am not that concerned about him ... I was concerned about him when he had taken over a country, I was concerned about the fact that he was basically running Afghanistan and calling the shots for the Taliban."

"LONG STRUGGLE"

Bush repeated his mantra that the war on terrorism would be long and difficult and extend well beyond the borders of Afghanistan. U.S. military advisers already are in the Philippines and soon will go to Yemen and Georgia to train local forces in the anti-terror campaign in those countries.

"If we find a training camp we'll take care of it, either we will or our friends will," he said. "We're working closely with other governments to deny sanctuary or training or a place to hide or a place to raise money. We've got more work to do."

"This is going to be a long struggle."

Saying he was more concerned that U.S. troops fighting the remnants of bin Laden's al Qaeda group as well as Taliban forces were well-equipped and supported, Bush predicted there would be more fierce battles like that fought in the past two weeks in eastern Afghanistan in which eight Americans died.

"There's going to be other struggles like Shahi Kot and I'm just as confident about the outcome of those future battles ... We are showing the world we know how to fight a guerrilla war with conventional means," he said.

Pentagon officials have said that the now-waning 12-day U.S.-led military air and ground assault in the Gardez region has killed hundreds of hard-line al Qaeda and Taliban fighters, but that fewer than 20 have been taken captive.

A senior Afghan general said that U.S. and Afghan troops overran the remnants of hundreds of regrouping Taliban and al Qaeda rebels around Shahi Kot on Tuesday, sending them fleeing towards the Pakistan border and effectively ending the biggest battle of the Afghan war.

U.S. and Afghan troops along with other Western forces on Wednesday continued mopping up operations in the battle area 95 miles (150 km) south of Kabul and 20 miles (32 km) east of Gardez, the capital of Paktia Province bordering Pakistan. Nampa-Reuters