LISBON, Portugal (AP) _ Ancient stone carvings threatened by a $1 billion dam project may be only 3,000 years old, not Stone Age art as originally believed, according to archaeology reports released Friday.

The reports, commissioned by the state-owned utility Electricidade de Portugal, add fuel to the debate over whether the open-air engravings should be saved from the planned Foz Coa dam. Building has slowed since their existence was revealed in December.

Portuguese archaeologists and Stone Age art expert Jean Clotte of France say the Coa carvings, 270 miles northeast of Lisbon, are the world's largest gallery of open-air Paleolithic art.

Clotte, commissioned by UNESCO, estimated the oldest etching to be 20,000 years old.

However, the report by Australian archeologist Robert Bednarik said none of the Coa carvings could be older than 6,000 to 8,000 years at most. Excerpts of the report were printed in the newspaper O Independente.

``It is quite certain that a proportion of the petroglyphs that were labeled Paleolithic are in fact under 3,000 years old,'' said Bednarik, president of the Melbourne-based International Stone Age Art Federation.

Portuguese archeologists dismissed the reports as ``cheap propaganda'' for the utility and questioned dating methods used.

In another report, Australian scientist Alan Watchman shortens the age even further to 100 and 1,700 years old, judging by the carvings' similarity to railroad quarry etchings.

Some 200 archaeologists in Portugal and various university organizations have mobilized to demand the river valley be turned into a national park.

Prime Minister Anibal Cavaco Silva's government must make the final decision.