An archaeologist's treasure-trove lies hidden in old wrecks at the bottom of the Aegean Sea, open to looting and the ravages of time.

Some 7,000 years of trade and navigation across the eastern Mediterranean by Greeks, Phoenicians, Egyptians, Persians and others have left hundreds of wrecks littering reefs in Greek waters."Sometimes you can dive the same reef and find three completely different wrecks of a different history. You find a Roman wreck that lies on top of a Classical wreck and a modern wreck on top of that," professional diver and sea salvage expert Peter Nicolaides told Reuters in an interview.

"The wreck is more like an unlooted tomb. It is a concentrated collection of artifacts - the tools, the coinage - it's all there in one boat," he said.

Greece's Underwater Archaeological Service is the only organization allowed to conduct underwater digs, although it does run joint programs with foreign archaeological schools.

But its resources are mainly taken up with surveying coastal sites for antiquities before building permits are issued.

Director Dimitris Kazianis said that this summer the service planned preliminary work on the oldest wreck it has excavated, a vessel from the fifth century lying off the coast of the island of Rhodes.

Experts believe the ship was carring a cargo of amphoras, huge clay storage jars, from the island of Chios to Rhodes.

Excavations have also begun on a 17th-century wreck, the La Terese, off Crete and of a wreck off the island of Euboea.

Nicolaides said irreparable damage is done by organized looters working for private collectors and operating from yachts with 'moon pools' (pools inside the yacht) so divers can escape detection.