"It's a second death for Pompeii, but this time Vesuvius had nothing to do with it," a Rome art student said bitterly.

He was referring to the discovery in January that thieves had made off with 12 priceless frescoes from a middle-class home in ancient Pompeii, the Southern Italian city that on a long-ago-day in 79 A.D. was buried under six yards of ashes and lava from the Neapolitan volcano, Vesuvius.

The most recent in a series of thefts from Pompeii, the mysterious disappearance of 12 colorful panels ranging in length from 10 inches to two yards has focused attention on the spirling art thefts that are whittling away Italy's vast artistic heritage.

In the case of Pompeii, thieves were apparently able to cut the plaster paintings from the walls of House No. 25.Island III, and flee without leaving a clue because of the lengthy perimeter of the ruins makes tight surveillance difficult. An inadequate number of guards - 164 men and four dogs - no lighting or sophisticated alarm systems, made things even easier for the unknown robbers thought to have stolen on commission.

But the facts that curators in Pompei have been waiting for a year for a delayed special allocation of more than $3 million, and the post-theft discovery that no photographs of the frescoes exist in Italian state archives further dramatize the situation.

The failure of the Italian government to adequately protect its 30,000 churches, 600 museums, 20,000 castles and innumerable archeological sites has in fact led many art-conscious Italians to urge their foreign friends "to visit Italy before it's too late."

Since World War II, some 44,000 art thefts have been reported here, and the number of robberies has been growing so rapidly - 300 in 1957, 2,328 in 1968, 5,843 in 1972, and 10,952 in 1974 - that Italy's chief art sleuth, Rodolfo Siviero, once described his work as "like bailing out a sinking ship with a teaspoon."

Two major art robberies in 1975, the stealing of a Raphael and two Piero della Francesca's in February from the Ducal Palace in Urbino and the theft in May 28 paintings from the Milan Gallery of Modern Art led to some incipient changes.

The recently born ministery of cultural possessions was able to increase the country's museum guards from 3,000 to 5,000 (the final target is 9,000); additional positions for art historians, archeologists and other specialists, were created, at least on paper, and fund-raising attempts for sophisticated alarm systems was begun.

But with a labyrinthine bureaucracy these reforms have been slow in finding application. Surveillance is so lackadaiscal in so many Italian museums that according to one art dealer "robbery isn't even dangerous and many would-be thieves ate discouraged only by the difficulty of finding a willing buyer."

Italy's authorities can only gnash their teeth when they learn that a Simone Martini crucifix tha disappeared from Pisa was bought in good faith by an English collector or that Lorenzo Monaco's "Madonna with Child" is on view in the Museum of Stockholm. But a year after their disappearance Urbino got its three masterpieces back because the thieves had been unable to find any willing takers.

Even more extensive than bona fide art thefts, however, is the astronomical number of "stolen" archeological objects which have been brought to light by clandestine and illegitimate excavations.

Thus from 1970 to 1974 alone some 41,592 otherwise unknown antiquities of varying value, size and shape were discovered, many in private homes, by Italian police.

In ancient Etruria, north of Rome, modern tomb robbers or "tombaroli" do a flourishing business in Etruscan artifacts, many of which turn up on Sundays on the stands at Rome's "Porta Portese" flea market.

Others - once an entire Etruscan tomb was involved - make it across the border to Switzerland or to Corsica where they are restored, sold and exported elsewhere. And still other objects, like the now-famous "Euphrorius Krater" even end up in as repectable a place as New York's Metropolitan Museum.

Addtional damage is done by average Italians who contest the government's claim that any antiquity found in Italian soil is property of the state. Rome's "Appia Antica" and its Imperial Forum have thus been stripped almost bare by private scavengers eager to decorate a characterless living room or spruce up a faded villa garden.

Another thorn in the side of Italian art lovers is the neglect that recently led a member of Italy's conservationist society, "Italia Nostra" to joke "come and see our museums, while we still have them."

Experts say hundreds of thousands of works of art are piled up in dusty cellars on storehouses and are thus unavilable to the public eye. Other museums, like the Torlonia Museum on Rome's Via Lungara, have been closed for decades. And the country's Central Cataloging Institute is divided among four separate Roman buildings, three of which are in dusty, overcrowded condition.

Because of the poor organization of Italy's museums, a well-known antiquities fence in Switzerland told an Italian journalist, "I don't feel guilty."

Italy's museums, he told a reporter from the Milan paper Corriere della Sera, "leave at least 80 per cent of the works they have buried in the cellars." By getting them out of the country, he argued, at least someone gets to see them.

A spokesman for the ministry of cultural possessions said the museum situation had suffered a temporary setback because of the current recession. "But even if we reorganized our museums" he said, "we'd still have a theft problem. After all this country is really one big open-air museum and we'll never be able to have guards everywhere at once."

The only real solution, he said, was that of sensitizing public opinion. "Otherwise our artistic heritage will just keep on disappearing, bit by bit."