Some senior Al Qaeda and Taliban officials are believed to be in Kunduz, the Taliban's last city in northern Afghanistan, a U.S. official said Friday.

While Usama bin Laden and Taliban leader Mullah Mohammed Omar are probably in the southern part of the country, some of their deputies and lieutenants have been caught up north, the official said, speaking on the condition of anonymity. The official declined to provide specific names.

The northern alliance is also on the move in southern Afghanistan after a week of consolidating their gains. Advance elements of a northern alliance force have entered Helmand province, one of the last areas of the country still regarded under Taliban control, the official said.

The force, led by Ismail Khan of Herat and aided by U.S. forces, is on the road that connects Herat to Kandahar, the Taliban's spiritual capital and home to Mullah Omar. But it's unclear whether the fighters have enough numbers or weapons to capture the city for the alliance.

U.S. intelligence officials are skeptical of any reports of a negotiated surrender between the alliance and Taliban troops at Kunduz, the official said. Some alliance officials have claimed an agreement will be in place by Sunday.

Some of the negotiations hinge on the fate of the foreign Al Qaeda fighters in Kunduz, who are less willing to surrender than their Afghan allies, the U.S. official said.

It was unclear what each side was proposing. The United States has insisted that suspected members of bin Laden's Al Qaeda network not be allowed to go free as part of any deal.

At least 3,000 Taliban and Al Qaeda fighters hold Kunduz, where many rallied after fleeing from other Taliban-held areas that fell to the northern alliance.

Fighting was reported near the town of Khanabad, about 20 miles east of Kunduz, where alliance forces appeared to be probing Taliban positions, the official said.

U.S. bombing of Afghanistan continued through the Thanksgiving holiday, as carrier-launched airstrikes zeroed in on tunnels and caves believed to contain Al Qaeda and Taliban leaders and supplies, as well as Taliban troop concentrations, Pentagon officials said Friday. American cargo planes dropped rations, wheat and blankets near Kunduz and Herat, in western Afghanistan.

In the northern Arabian Sea, hundreds of Marines waited aboard ship for the go-ahead to set down in Afghanistan. The Pentagon probably will send up to 1,500 Marines into Afghanistan, officials have said.

They would come from one of two Marine Expeditionary Units based on ships in the Arabian Sea off the coast of Pakistan. Those troops are trained for quick raids, counterterrorism and urban warfare, as well as reconnaissance and more traditional forms of combat.