The sites were targeted as part of the military attacks to stop the Yugoslav government of President Slobodan Milosevic from uprooting tens of thousands of ethnic Albanians.

Air Force major general Charles Wald told reporters that fuel production, storage and transportation were targeted for air strikes by NATO forces during the past two weeks.

"His (Milosevic's) fuel production, distribution and storage has been hit hard," Wald said.

The strikes by pilots with NATO have hit the 107,000 barrel per day refinery in Pancevo and the 60,000 bpd one in Novi Sad, as well as strategic fuel storage depots around the country.

Attacks against Danube River bridges, rail lines and other infrastructure has made it difficult for the Serbs to move their remaining fuel to military and police units, Wald said.

"Idon't think they (NATO aircraft) have seen any (military vehicles) running out of gas. And if they are stopped, we're not sure if they're out of gas or just taking a coffee break," he said. "But our indications are they are starting to have difficulty and they are starting to husband their fuel a little bit more."

Wald said he could not estimate how much of Serbia's oil refining capacity had been hit.

"I am not sure what the percentage was. But a significant percentage of their ability to produce POL (petroleum, oil, lubricants) for military use has been struck," he said.

On Tuesday, navy rear admiral Thomas Wilson said the Novi Sad refinery had halted operations because of the attacks, and that Pancevo may be out of commission as well.

The country has an estimated 100 or so fuel storage facilities, including some for civilian use. NATO forces have targeted the military fuel depots as well as pumping stations, trucks and transshipment locations for rail cars to load fuel.

Yugoslavia pumps about20,000 bpd of crude oil, and imports another 60,000 bpd from other suppliers.