An avalanche of snow buried 20 cars near a tunnel leading through some of Afghanistan's highest mountains yesterday, a U.N. spokesman said. There was no immediate word on casualties.

The cars were buried in snow outside the Salang tunnel, about 80 miles north of the capital, Kabul, on the main road to the country's north, said the spokesman, Yusuf Hassan.

He said it was not clear how many people were trapped in the vehicles or if there were casualties.

The Afghan government asked for international assistance to rescue people in the cars and the British-led peacekeeping force in Kabul sent a helicopter to the scene, Hassan said.

But he said the United Nations does not have snowplows or bulldozers in the area.

During the past few days, snow has blanketed parts of Afghanistan, blocking roads and isolating remote mountain villages.

Hassan said that U.N. relief agencies have emergency supplies in many large towns but are concerned that villages could run out of food if they are cut off for more than a few days.

"The snowfall is blocking off huge areas of Afghanistan," he said.

Helicopters needed to deliver vital humanitarian aid have been grounded in nearby Dushanbe, Tajikistan, Hassan said. Earlier, peacekeepers said that Kabul airport was closed because of the snow.

Millions of Afghan civilians depend on international food aid for survival.

The parking lot outside the office of Dr. James Graves always seemed to be full of people waiting to see him. Some patients ate lunch as they passed the time, while others worked on their cars.

"Some of them were staggering," recalled Russell Poerner, a physical therapist who worked next door to the practice in suburban Pensacola. "Some of them were holding on to cars for balance."

According to prosecutors, Graves was running an illegal -and deadly- "pill mill" for addicts and dealers who paid him hundreds of thousands of dollars for prescriptions of the painkiller OxyContin and other drugs.

Graves, 54, is now on trial on manslaughter charges in the OxyContin overdose deaths of four patients.

He is believed to be the first doctor in the country to stand trial on manslaughter or murder charges in the deaths of patients who had been prescribed Oxycontin. At least two other doctors are awaiting trial.

"If you came in and said you had pain, you got prescriptions," prosecutor Russell Edgar told the state jury. "There was no record of any treatment because there was no treatment."

Graves, who was arrested in June 2000, is offering the same defense as the other doctors: The patients died because they abused the drug.

Under sentencing guidelines, Graves could get 15 to 30 years in prison if convicted on all counts of manslaughter, racketeering and unlawful delivery of a controlled substance. The prosecution rested Monday and the defense started its case Tuesday.

OxyContin, introduced six years ago, is a slow-release narcotic that lasts about 12 hours. It is prescribed for victims of moderate to severe chronic pain from such problems as arthritis, back trouble and cancer. But addicts have found they can get a quick, heroin-like high by chewing the pills or crushing them and snorting or injecting the drug.

The Drug Enforcement Administration blames OxyContin for 117 deaths in the past two years and suspects the drug in 179 other deaths.

The drug's maker, Purdue Pharma of Stamford, Conn., says the number of deaths tied to the drug has been exaggerated, but it took the strongest version of OxyContin off the market last year.

Graves is a former Navy doctor who was fired from a Pensacola pain center in 1998 after selling pills to patients in parking lots and failing to record prescriptions in patient records, according to his employer, Dr. Thomas Hutchinson.

Witnesses testified that Graves wrote prescriptions from his front porch before he opened his practice. He allegedly told authorities he saw 50 to 60 patients a day at his Pensacola-area practice and wrote 200 prescriptions every day. His wife estimated he had 1,000 patients at the time authorities closed down his practice.

By the time he was arrested, Graves was Florida's top OxyContin prescriber, insurance records show.

The drug combinations that he prescribed came to be called "Graves cocktails" by area pharmacists.

Two dozen pharmacists testified that they stopped filling Graves' prescriptions, which typically included OxyContin, the painkillers Lortab and Vioxx, the tranquilizer Xanax and the muscle relaxer Soma.

A planned $40 million copper concentrate leaching demonstration plant should begin operating in early 2003, Phelps Dodge Corp. announced yesterday.

Construction is expected to begin in the central Arizona town of Bagdad in the second quarter of this year.

The plant is designed to recover commercial-grade copper cathode.

The facility will process 150 tons per day of concentrate produced by the existing mill and flotation operation.

At full capacity, it is expected to produce 35 million pounds annually of copper cathode from concentrate. That would account for about 15 percent of Bagdad's total copper production capacity, the company said.

Phelps Dodge is the world's second largest producer of copper.