CAIRO, JAN. 3 -- Egyptian archeologists have found a priceless collection of Byzantine gold coins in the ruins of a 4th-century Coptic monastery, the head of the government's antiquities department said today.

Calling it the biggest and most important numismatic find in 120 years, Egypt's top archeologist, Ahmed Kadry, said the treasure consisted of 820 gold coins, or solidus, dating to the 6th and 7th centuries A.D.

The treasure was found last month during restoration work on the White Monastery, founded in the 4th century by Father Shenudah, near the city of Sohag, about 300 miles south of Cairo, Kadry said.

Egyptian archeologists recovered the treasure in two parts. The first, found Dec. 17, consisted of 400 gold coins in pottery jars that were buried below a monk's cell at the monastery. It included 220 large coins and 180 smaller ones, Kadry said.

The second collection was found Thursday. It consisted of 301 large pieces and 119 smaller pieces, also hidden in small pottery jars beneath another cell.

"This is the largest and most important find of a collection of coins in the history of the Egyptian Antiquities Department," said Kadry, displaying the gold and the pottery.

He said the coins date to the Byzantine emperors Justinian (527-565), Phocas (602-610) and Heraclius (610-641).

The two faces of each coin carried pictures of the emperor of the time, with a crown over his head and a cross in his hand and the letters "con" -- a reference to the city of Constantinople, the ancient name of Istanbul, the center of the Byzantine empire.

"In addition to the priceless archeological value of the two groups, they also have great scientific value," Kadry said. "They are expected to shed important light on the history of coin minting, the transition from Byzantine coins to Arab coins."

Kadry said archeologists also would study why the coins were hidden in the monastery. "But, and this is my personal opinion, I think that Father Shenudah, founder of the monastery, led some sort of peaceful resistance to the Byzantine occupation of Egypt. He probably protected the treasure against the extortion of Byzantine authorities."

The Copts of this age also opposed the Christian beliefs of the Byzantine rulers, Kadry said, "and the conflict, in one of its aspects, was related to religion."

The Coptic Church, at the Council of Ephesus in 451, adopted a monophysite creed -- believing that Jesus Christ had one nature or a composite nature of both the human and the divine -- and broke away from the rest of Christendom.

Gawdat Gabra, director of Cairo's Coptic Museum, agreed with Kadry, saying the presence of the gold could have been related to the conflict between Copts and Byzantines, which he said was political and economic as well as religious. The monasteries in those days were centers of economic activity and their products were sold in nearby towns and villages, he said.