U.S. special forces discovered hundreds of pounds of explosives, as well as rockets and other bomb-making materials, hidden in feed sacks in a city in eastern Afghanistan, an American military spokesman said Monday.

The explosives were found Friday in Jalalabad, said Col. Roger King, a spokesman at the U.S. military headquarters in Bagram. Along with the 900 pounds of explosives, troops found 200 rocket-propelled grenades and 180 pounds of ball bearings.

"The explosives and ball bearings could indicate someone was planning to prepare an improvised explosive device," King said.

Jalalabad is about 60 miles east of the capital, Kabul, near the Pakistani border.

U.S. forces searching Afghanistan for Al Qaeda and Taliban leaders continue to turn up dozens of weapons caches each month. They are either destroyed or given to the Afghan army.

In October, U.S. troops used C-4 explosives to destroy hundreds of 500-pound bombs buried in a dry riverbed near Kandahar.

Meanwhile, attackers fired a single rocket at a U.S. base in the eastern town of Khost, King said. Nobody was injured in the Saturday night attack. The rocket landed several hundred yards from the base perimeter.

U.S. bases in Afghanistan are attacked several times a week, usually with crude rockets set off by remote control or timers. The rockets rarely hit their targets and damage is minimal.

On Saturday, five Afghan men were injured by remnants of ordnance that exploded in Khost. Two had to be airlifted to Bagram for treatment. All were in stable condition Monday.