KABUL (Reuters) - Afghan Defense Minister Mohammad Qasim Fahim rejected on Saturday speculation of a rift with President Hamid Karzai that the United States fears could undermine the fledgling post-Taliban administration.

"I can explicitly say...that this issue is totally far from reality," the powerful minister, a senior figure in the Northern Alliance which ousted Afghanistan's former Taliban rulers, told a news briefing.

"I can assure (you) that in the cabinet and in particular between me and Karzai there is no difference and we have close and sincere working relations," he said.

In a sign of how worried the United States was about foreign media reports of a split, its special envoy for Afghanistan, Zalmai Khalilzad, met the two men this week.

"If (relations) were bad in the past, now they have improved," Khalilzad said afterwards.

Fahim is believed to have been furious that Karzai asked U.S. special forces to guard him instead of the Northern Alliance, but the defense minister told the briefing he supported the move.

"They (Karzai's bodyguards) have come just for...improvement of security arrangement...and this is a temporary move," he said.

The two men are from different ethnic groups -- Fahim is Tajik and Karzai is Pashtun -- which it was feared could deepen suspicion and mistrust between the tribes in Afghanistan.

Fahim told reporters the rumors of the rift with Karzai had been circulated by al Qaeda and Taliban sources as well as "specific enemies," an apparent reference to neighboring Pakistan which once backed the Taliban.

SUPPORT FOR U.S. TROOPS

Fahim told the news briefing he supported the presence of U.S. troops in the war-ravaged country until al Qaeda fighters and other militant threats were "annihilated altogether."

The U.S. commander for Afghanistan, General Tommy Franks, said on Thursday his troops could be in Afghanistan for years.

"Concerning the remarks of General Franks, I comment that still al Qaeda and their bases exist in Afghanistan...and especially around the southern borders of Afghanistan.

"Any moment there is the possibility of destabilisation of the situation and their attacks," he added.

Thousands of U.S. troops are hunting for remnants of the ousted Taliban and the al Qaeda network they sheltered. Al Qaeda, led by Saudi-born dissident Osama bin Laden, is blamed for the September 11 air attacks on New York and Washington.

"Whenever we come to the conclusion jointly with the U.S. military that the danger of terrorism is annihilated altogether, I am certain that there will be no need felt for the presence of American soldiers," Fahim said.

"The American forces spontaneously will deliver their bases to the national Afghan army after it manages to stand on its feet...and they themselves will go back to their country."

Fahim told Reuters after the briefing that he believed bin Laden and Mullah Omar, leader of the ousted Taliban, were alive. He did not say whether he knew where they were or on what evidence he based his assessment that they were still alive.

He branded renegade warlord Padshah Khan Zadran, until recently an ally of U.S. forces in their hunt for al Qaeda, a "criminal and fugitive...greedy for power."

Zadran, who is in the southeastern area of Khost, was sacked as governor of the Paktia province earlier this year. He later showered the provincial capital of Gardez with missiles that killed an estimated 30 civilians.

Fahim also used the rare media outing to call on the international community to come forward with promised cash to help rebuild a country ravaged by over 20 years of war.