Cores drilled at a location at the mouth of the River Tiber have revealed the site of a port whose existence has been sought for centuries, it said in a press release.

The port lies northwest of Ostia, which was established by Rome as a fortress gateway to enable trade to pass upriver towards the city and prevent pirates and marauders.

The evidence points to a port established between the fourth and second century BC and had a depth of six metres (20 feet), making it accessible to sea-going vessels, the CNRS said.

Rome emerged as the prime power of the Mediterranean thanks in part to trade. It imported huge amounts of wheat, especially from Egypt.

In the first century AD, the grain port at Ostia was superseded by a giant installation covering 200 hectares (500 acres) at Portus.