U.S. special forces scored another victory Wednesday by confiscating thousands of weapons from a local warlord.

Special forces and their anti-Taliban allies searched house-to-house for Al Qaeda and Taliban renegades in four villages in the southern province of Helmand. Afghan sources said they were also searching for the Islamic militia's deposed supreme leader, Mullah Mohammed Omar.

The search turned up no trace of Omar, who refused to turn over bin Laden for his role in the Sept. 11 terrorist attacks in the United States.

However, about 2,000 weapons, ranging from small arms to heavy artillery, were confiscated, according to Khalid Pashtun, an aide to Kandahar Gov. Gul Agha.

Pashtun said the weapons were taken without incident Wednesday from Haji Bashar, a local warlord in Helmand province, as part of a campaign to bolster security in the region.

Helmand and other southern provinces were Taliban strongholds and among the last areas handed over by the Islamic militia after it collapsed last year following intense American airstrikes and attacks by the U.S.-backed northern alliance.

The U.S.-led coalition has been trying to get weapons out of the hands of local warlords whose support for the new interim Afghan government is in doubt. The United States has allied itself with other power brokers, including Agha, in hopes they can maintain order and work with the central government in Kabul.

Last week, efforts to collect weapons triggered brief clashes near the northern city of Kunduz with local leaders who did not want to surrender their guns, Afghan sources said on condition of anonymity.

Although the U.S. bombing campaign is largely over, U.S. special forces have intensified the search for remaining Taliban and Al Qaeda members. The search, however, has been complicated by rivalries among tribal leaders, some of whom switched sides during the fighting last year.

In Khost, several warlords are competing for recognition by the U.S.-backed government of Hamid Karzai.

On Wednesday, the Afghan Islamic Press, based in Pakistan, reported that fighters loyal to one of them, Zakim Khan, had captured most government, military and intelligence facilities in Khost from loyalists of a bitter rival, Bacha Khan Zadran.

Zakim Khan told the agency that he wanted Karzai to send a delegation to mediate the standoff.

But Amanaullah Zadran, brother of Bacha Khan and the government's minister of border and tribal affairs, said by telephone that his brother's forces were in complete control and that there had been no fighting.

Amanullah said three tribes had told Khan to leave Khost by Thursday. Other Afghan sources, speaking on condition of anonymity, confirmed tensions were running high in the Khost area, where Army Sgt. 1st Class Nathan Ross Chapman was killed in an ambush Jan. 4, the first U.S. soldier killed in combat.

In other developments, FBI Director Robert Mueller paid an unannounced visit to the U.S. military base outside Kandahar and said that Al Qaeda prisoners detained by U.S. forces have provided valuable information that has prevented new attacks against U.S. targets worldwide.

"Information we have picked up since the war has prevented additional attacks around the world," Mueller said. "Interrogations from Al Qaeda members detained here in Afghanistan as well as documents ... has prevented additional attacks against U.S. facilities around the world."

Mueller refused to elaborate. However, one prisoner — Al Qaeda training camp commander Ibn Al-Shaykh al-Libi — spoke of plots to bomb the U.S. Navy base in Bahrain and the U.S. Embassy in Yemen, according to U.S. and Yemeni officials.

Ibn Al-Shaykh al-Libi spoke of the Navy plot, said two U.S. officials, speaking on the condition of anonymity. Authorities, however, aren't sure if the threat was real.

The officials also confirmed that al-Libi provided information about Al Qaeda plans to use a truck bomb to blow up the embassy this week. U.S. officials said it was unclear if the plot had been verified and had no information on any arrests or discovery of bomb materials by Yemeni officials.

Last month, Singapore authorities arrested suspects they said were plotting attacks against the U.S. Embassy and other targets. The authorities said handwritten notes and a videotape found in Afghanistan helped lead them to the suspects.

Meanwhile, Gen. Tommy Franks, the commander of the U.S.-led campaign in Afghanistan, said that the United States is not planning a permanent military presence in Central Asia.

Franks said in Bishkek, Kyrgyzstan, said the United States would work with regional leaders to determine how long a U.S. military presence would remain.

"We have no plans to build a permanent military base" in Central Asia, he told reporters.

The Associated Press contributed to this report.