The plane was en route from Zahedan, on the Pakistan border, to Kerman, about 500 miles southeast of Tehran, Tehran television reported. It crashed in a mountainous area about 20 miles from its destination.

The Russian-made Antonov airliner operated by Iran's military lost contact with the control tower at 5:30 p.m. Wednesday, according to the reports.

The official Islamic Republic News Agency said rescuers had reached the crash site and that all 302 people on board had been killed, making the crash the deadliest in Iran's history. The death toll surpassed the 290 killed on July 3, 1988, when an Iran Air A300 Airbus was shot down over the Persian Gulf by the USS Vincennes.

The agency said the plane's passengers and crew were all members of the Revolutionary Guards. Earlier reports said 270 were aboard, but the latest media updates didn't explain the increase.

State television and radio did not offer reasons for the crash and did not address the possibility of terrorism. There was heavy snowfall in many parts of Iran on Wednesday, including in Zahedan, which hadn't seen snow in three years.

Tehran television quoted an anonymous official as saying the forces had visited the Sistan-Baluchestan Province, of which Zahedan is the capital, for an "important mission."

The Revolutionary Guards, under the direct control of supreme leader Ayatollah Ali Khamenei are seen as the defenders of Iran's Islamic regime. The guards protect Iran's borders and defend ruling hard-liners in this ultra-conservative society.

The government issued a statement offering condolences to the families of the victims, television and radio reports said.

Iranians were preparing for an Islamic holiday on Thursday, the feast of Velayat, when Shiites believe Islam's prophet Mohammad appointed his son-in-law, Ali, as his successor.

Wednesday's crash was the latest in a string of air disasters in Iran mostly involving Russian-built aircraft.

A Ukrainian An-140 aircraft flew into a mountainside Dec. 23, 2002, while preparing to land at an airport near the central city of Isfahan, killing all the estimated 46 scientists aboard.

In February 2002, a Russian-made Tupolev Tu-154 airliner, carrying 119 people, smashed into snow-covered mountains not far from its destination of Khorramabad, 230 miles southwest of Tehran.

(China Daily February 20, 2003)