An American researcher claimed Sunday to have discovered the remains of the legendary lost city of Atlantis on the bottom of the east Mediterranean Sea, but Cyprus' chief government archaeologist was skeptical.

Robert Sarmast (search) said sonar scanning 50 miles southeast of Cyprus revealed man-made walls, one as long as 2 miles, and trenches at a depth of 1,640 yards.

"It is a miracle we found these walls as their location and lengths match exactly the description of the acropolis of Atlantis provided by Plato in his writings," Sarmast said, referring to the ancient Greek philosopher.

The chief government archaeologist of Cyprus (search), Pavlos Flourentzos, reacted with skepticism, telling The Associated Press: "More proof is necessary."

Sarmast, 38, is an architect by training from Los Angeles. He has devoted the past 2½ years to trying to locate the lost city described by Plato in his dialogues, the Timaeous and the Critias. He spoke to reporters on the "Flying Enterprise," his expeditionary ship, after six days of taking highly sophisticated "side scan" sonars of the seabed.

He said he had chosen the area from data provided by two earlier sonar scans of the east Mediterranean by Russian and French expeditions. His own expedition used more sophisticated equipment, he said.

"We found more than 60-70 points that are a perfect match with Plato's detailed description of the general layout of the acropolis hill of Atlantis (search). The match of the dimensions and the coordinates provided by our sonar with Plato's description are so accurate that, if this is not indeed the acropolis of Atlantis, then this is the world's greatest coincidence," he said.

Tests of that part of the seabed showed it had once been above sea level, he said.

"We cannot yet provide tangible proof in the form of bricks and mortar as the artifacts are still buried under several meters of sediment at a depth of 1,500 meters (1,640 yards), but the evidence is now irrefutable," he added.

Asked if the ruins could not be that of another city that sank beneath the waves, Sarmast said the remains match Plato's description of Atlantis so closely that they could not be anything else.

"If you compare it with Plato, you will be astonished," he said. "We hope that future expeditions will be able to uncover the sediment and bring back physical proof."

Plato wrote of Atlantis as an island in the western sea, which has been widely interpreted to mean the Atlantic Ocean. An earthquake undermined the island and it was submerged. But societies dedicated to finding Atlantis remain.

For its time, Atlantis was a highly civilized nation and in legend it has become associated with utopia. The English philosopher Francis Bacon called his 1627 book on the ideal state The New Atlantis.

Chief government archaeologist Flourentzos said it was possible that Atlantis was near Cyprus.

"The myth of Atlantis has been around for ages and it is generally believed that, if it ever existed, it was somewhere in the Atlantic Ocean — hence its name. But ancient cities and civilizations in the Mediterranean region, such as the Minoan civilization of Crete, have disappeared as a result of major volcanic eruptions and earthquakes. For all we know, Atlantis may well have existed in our region."

Sarmast said his expedition had cost about a $250,000. The funds came from public donations to his US-based company "First Source Enterprise," which is devoted to the project, sales of his book "The Discovery of Atlantis," and the Cypriot Tourist Organization, which donated $60,000.

He said the book, published in September 2003, said Atlantis was in the east Mediterranean and his latest sonars confirmed it.