Two Roman-era shipwrecks have been found in deep waters off Greece's western coast, challenging the theory that ancient mariners stuck close to coastal routes for safety.

Greece's culture ministry says two second-century wrecks were found earlier this month in waters over a half-mile deep off the islands of Corfu and Paxoi.

A ministry statement says the wreckage was found in an area where a Greek-Italian gas pipeline is to be located, the Associated Press reports.

A Greek oceanographic vessel using side-scan radar and robot submarines took footage of scattered pottery, ballast stones and what could be remains of the wooden ships, the AP reports.

The team also raised samples of pottery and marble artifacts.