The excavation was begun prior to the issuing of building permits for a new wing of the Megiddo prison, which houses security prisoners. Some 60 inmates from the Megiddo and Tzalmon prisons took part in the excavation.

The site is close to Tel Megiddo, believed to be Armageddon of the New Testament book of Revelation.

The northern inscription mentions a Roman army officer who donated the money to build the floor. The eastern inscription commemorates four women, and the western inscription mentions a woman by the name of Ekeptos, who "donated this table to the God Jesus Christ in commemoration."

The mosaic also contains geometric patterns and a medallion with a fish design.

"I was told these were Byzantine," Di Segni said, "but they seem much earlier than anything I have seen so far from the Byzantine period. It could be from the third or the beginning of the fourth century."

A pottery vessel discovered at the site confirms Di Segni's dating, however she said the church's age can only be determined with certainty after excavators reach the level below the floor. "The problem is that in Israel we have no mosaic inscriptions from this period, and they will have to be compared with inscriptions from Antioch or Rome," she said.

Christian rituals were prohibited in the Roman Empire prior to the year 313 CE, and Christians had to pray in secret in catacombs or private homes. The earliest churches, dating from around 330 CE, are the Holy Sepulcher in Jerusalem, the Nativity in Bethlehem, and Alonei Mamre near Hebron. However, they contain only scant remains of the original structures, which were built by Emperor Constantine I.

The structure discovered at the Megiddo prison is a simple rectangular one lacking the later characteristics of churches, such as an apse facing east. "I don't know if this structure can even be called a church," Di Sengi said.

Other discoveries at the prison include dwellings from the Roman times and a ritual bath, which was sealed and built on top of during the Byzantine period, bearing out historical information about a Jewish site in this area, Kfar Othnai, which became a Christian site in the Byzantine period.

The excavation was directed by Yotan Tepper of the Israel Antiquities Authority.

Tourism Minister Avraham Hirchson said the discovery could greatly increase tourism to Israel.

"If we nurture this properly, then certainly there will be a large stream of tourists who could come to Israel. There is great potential and together with the evangelical center in the north could bring great strides in tourism," he told Channel Two.