Mexico City, Jul 27 (IANS/EFE): Mexican archaeologists have discovered a 1.5 tonne stone relief that was created more than 2,800 years ago, authorities said.

The discovery was made at the archaeological site of Chalcatzingo in Morelos state, "the only pre-Columbian site known in central Mexico with large bas-reliefs", said the National Institute of Archaeology and History, or INAH, in a communique.

The work - standing more than 1.5 meters tall - was discovered in late April on the north slope of Chalcatzingo as archaeologists were building a containing wall and protective roofs for the other monoliths in the area.

Sculpted on the stone are three cats sitting in profile, looking west and surrounded by great scroll decorations.

The relief was found broken in 11 pieces, which the experts spent May and June restoring, so that only now is it possible "to admire the triad of felines in their entirety", INAH said.

Since the first explorations there in the 1930s, some 41 monuments have been discovered in Chalcatzingo up to now, four of which have cat figures, animals feared and venerated by the Olmecs, who inhabited the area between the years 800-500 B.C., a period known as the Middle Pre-Classical.

Experts believe that the Olmecs, the first civilization in the Americas to leave monumental architecture and sculptures, built a frieze all along the Chalcatzingo hill.

The Olmec civilization flourished between 1800 B.C. and A.D. 400 in the region occupied today by the states of Veracruz and Tabasco.