An underwater cave decorated with dozens of drawings and engravings dating to 10,000 B.C. has been discovered by sheer accident by a French diver, the Culture Ministry said Friday.

Culture Minister Jack Lang classified the site near Cassis, east of Marseille, as a historical monument and named it after Henri Cosquer, the professional diver who found it last summer.The discovery was kept secret to allow scientists to fully and safely explore the cave and its surroundings, the statement said, adding that the entrance has been sealed.

Underwater archaeologists believe the cave is as important as the Lascaux caves near Switzerland, famous for their beautifully preserved colored portrayals of animals and prehistoric life.

The cave opening was discovered about 120 feet below sea level. A narrow, sloping corridor - also underwater - led to the cave itself, which is several dozen yards wide and 13 feet high. The cave lies slightly above sea level.

"The paintings and drawings date to the end of the paleolithic era, probably the magdalenien era, that is, about 10,000 B.C.," said Robert Chenorkien, director of the Prehistoric and Anthropological Laboratory at the University of Aix-en-Provence.

Prehistorians say sea level was almost 400 feet lower in that era.