TOKYO (Reuters Life!) - A researcher investigating underwater rock formations off the coast of Japan believes they are the remnants of an Asian equivalent of Atlantis -- an ancient civilization swallowed up by the ocean.

Marine geologist Masaaki Kimura says he has identified the ruins of a city off the coast of Yonaguni Island on the southwestern tip of Japan.

He has worked for decades to prove the rocks found by scuba diving tourists in 1985 are from an ancient city, which he says may have sparked the fable of Mu -- a Pacific equivalent of the tale of the lost city of Atlantis.

“Judging by the design and the disposition of the ruins, the city must have looked just like an ancient Roman city,” said Kimura, a professor at Ryukyu University and the chairman of the non-profit Marine Science and Culture Heritage Research Association.

“I can envisage a triumphal arch-like statue stood on the left side of the Colosseum and a shrine over the hill,” he told Reuters Television.

Some of the initial divers notices the rocks were unnaturally smooth and formed a sort of staircase near the island’s shores. Subsequent dives by Kimura revealed irregular rock outcrops over 1 square km (0.4 square mile) and mounds of rubble.

Kimura says he believes the city had a castle, a shrine, an arch, statues and a colosseum.

“In my estimation, the castle was situated right in the middle of the city. And though not as big as the castle, a lot of ruins of shrine-like structures too have been discovered,” he said at his research room.

Kimura believes the city was sunk in an earthquake 3,000 years ago.

However, many scientists dispute his claim, saying the ruins can be accounted for by natural phenomena such as tidal and volcanic activity. They also say that very few artifacts such as clay pots or weapons have been found to prove humans lived among the rock formation at all.

Kimura, however, remains convinced.

“I am getting close to a conviction that this is a mysterious civilization lost in a tectonic deformation in the Pacific ocean,” he said.