The BBC's Rome correspondent David Willey reports.

The five-year-programme of digs will be the biggest project of its type in Rome since World War II.

Plans for the excavation were drawn up after a first century Roman fresco painting was discovered near the ruins of the Colosseum.

The painting shows a bird's eye view of an unidentified ancient city and is unique for depicting an entire walled city with all its buildings, including a temple and public housing blocks.

Archaeologists believe the painting could be part of an important administrative building, which was later incorporated into the public baths built in the first century by Emperor Trajan.

Tombs raided

Further excavations will take place in the ruins of the Roman Forum and the Circus Maximus, where chariot and horse races were held.

Archaeology has traditionally received little government funding in Italy despite a plethora of ancient sites.

The Italian Culture Minister Valter Veltroni, who made the announcement, said that foreign archaeological schools will be invited to take part in the digs.

A BBC correspondent says that robbers continue to loot ancient Italian tombs and insufficient attention has been paid to conserving existing sites.