In addition to the temple, archaeologists have also unearthed about 10,000 artifacts, including a stone ax that could be 4,000 years old, the paper said.
The Japanese, who are behind the road project, are giving high priority to the survey before potentially damaging construction work begins.
Remains found at the temple include parts of a ceremonial hall, the base of a large Buddha image, smaller Buddha images, pottery and roof tiles, the paper said.
Large-scale construction did not recommence until the French arrived toward the end of the nineteenth century to colonize the country.