Italian archaeologists have found more than two dozen new tombs at the famed Etruscan burial grounds at Tarquinia north of Rome.

''This is the most exciting discovery here in decades,'' said the archeological superintendent for southern Etruria, Maria Tecla Castaldi.

So far 27 tombs have been added to the thousands at the site since a chance discovery during building work two months ago, she said.

''I've just been down and visited the only tomb that is open, which was probably broken into around 50 years ago,'' she said.

''The other tombs are sealed and presumably intact''.

Police have cordoned off the area, less than half a mile (500m) from the main necropolis, to ward off tomb raiders as digs go on. The well-preserved tombs at Tarquinia and nearby Cerveteri have been described by some experts as 'cities of the dead'. Experts believe the Etruscans wanted their deceased to have everything they might need easily to hand in the afterlife, and so crammed the tombs with everyday objects.

Archaeologists say women were buried in stone tombs separate from the men and that slaves were cremated and their ashes placed in urns besides their masters' remains.

The general span of the graves stretches from the seventh to the first century BC.

Excavations first began on the Tarquinia site in 1489 and since then over 6,000 tombs have been uncovered.

The Tarquinia tombs also have wall paintings, some probably dating back to the eighth century BC, depicting scenes from the lives of the dead.

The paintings give an insight into the habits and customs of the Etruscans, showing a refined, flourishing, and highly developed culture.

Experts say the later wall paintings show Greek and perhaps even Eastern influences, reflecting the cosmopolitan nature of this civilization.

Some of the most popular ones, such as a sexually explicit fresco from the Flagellation Tomb, have been posted on the Web.

The Etruscans lived mainly between the rivers Tiber and Arno in modern-day Umbria, Lazio and Tuscany, in the first millennium before Christ.

By the sixth century BC they had become the dominant force in central Italy, but repeated attacks from Gauls and Syracusans later forced them into an alliance with the embryonic Roman state, which gradually absorbed Etruscan civilization.

However, the Etruscans had the upper hand in the early days and supplied Rome with the last three of its first seven kings including the famous Tarquinius Superbus (Tarquin the Proud).

Like his predecessor Tarquinius Priscus, he was from Tarquinia. Most of what is known about the Etruscans derives from archaeology as the few accounts passed down by Roman historians tend to be hostile, portraying them as gluttonous and lecherous.

This problem is compounded by the fact that Etruscan cities were built almost entirely of wood and so vanished quickly, leaving little for archaeologists to investigate.

In 2004 Tarquinia and Cerveteri became Italy's 37th World Heritage Site.

They have since been joined by the Val d'Orcia in Umbria, the ancient Greek city of Siracusa and the Palazzi Rolli in Genoa.

With 40 sites including Venice, Rome, Naples, Florence, Siena, Pisa, Verona, Vicenza, Ravenna, Ferrara, Urbino, Assisi, San Gimignano, Pienza and the Amalfi Coast, Italy has more treasures on the UNESCO list than any other country. Among UNESCO's other ancient Italian listings are Pompeii, Agrigento and Emperor Hadrian's Villa (Villa Adriana) at Tivoli.