Rome, June 27 - A large number of beautifully decorated Etruscan urns, more than 2,000 years old, have been recovered by Italian police whose two-year investigation covered the entire peninsula, authorities said Thursday. At least 23 urns from the Hellenistic period, which ran from the third to the first century BC, were recovered by officers in a special culture branch of the Carabinieri military police. The investigation also uncovered a new site for archaeologists to excavate near the Umbria city of Perugia, in central Italy. Italy's minister of cultural heritage says the find will contribute to a better understanding of the ancient Etruscans, whose culture was swallowed up by the Romans. "It is a recovery of exceptional value," perhaps the most important in recent decades, Massimo Bray told a news conference in Rome, where some of the recovered urns were displayed. It is believed the urns were among as many as 3,000 pieces stolen from a large subterranean burial ground known as a Hypogeum belonging to the aristocratic Cacni family. The Hypogeum is now being carefully explored. Many of the urns are said to be intact and made from white Umbrian travertine, partly decorated with high reliefs of battle scenes and other ornaments. Authorities say they believe construction workers stumbled upon the ancient tomb as far back as a decade ago. But they did not report the find, including the urns and other archaeological pieces that were uncovered, so they could sell these to unscrupulous collectors. Police were tipped off when they caught a known dealer with photos of the finds as well as a small white travertine carved head. Police were also able to recover as many as seven ancient urns that had already been sold in Perugia, and managed to pinpoint the site of the discovery where archaeologists and federal government researchers are now working.