LIMA, Peru (AP) _ One day, guards at the University of Cuzco museum walked out with dozens of golden relics of the Incas. By the time police caught up with them, the thieves had melted down most of the treasures.

Among the items lost were 600-year-old figurines of a man and a woman that had been centerpieces of the museum collection.

It was an example of the plunder of Peru's cultural heritage that began with the Spanish conquistadors and continues with modern looters who rob museums, tombs, churches and private homes.

''It's a real catastrophe, a tragedy,'' said Luis Barreda, director of archaeology at the Cuzco museum. ''We've lost valuable pages of Inca history.''

Police tracked the thieves down only a day after the robbery in February. Even so, they had already melted down 54 of the 58 stolen figures, bracelets, necklaces, pins and ceremonial items.

The loss was estimated at $53 million, but ''The value in dollars is nowhere near as important as the intrinsic value,'' Barreda said. ''It was the best collection of metallic items we had in the museum.''

Some thieves are misled by myth and rumor into believing Inca relics are worth more as gold than as art, said Hernan Araoz Becerra. He directs the National Institute of Culture in Cuzco, which was the Inca empire's capital.

Incan artists did not work with pure gold, as many people believe, he said, but with alloys as low as eight karats, or one-third gold.

''What the thieves would have received for the metal was very little,'' Araoz said. ''Obviously, in their ignorance they thought they would be rich. They were mistaken.''

Stolen gold and silver pieces are not usually destroyed, as in Cuzco, but instead go to private collectors outside the country, said Maria del Pilar Remy, director of the Archaeology and Anthropology Museum in Lima.

Although it is illegal to export antiquities, ''There are private collectors who practically commission for these things,'' so thieves ''perform these robberies on request,'' she said.

Well-known objects that might be risky to sell intact sometimes are broken up and sold in pieces, jewels to one buyer and metal to another.

A week after the Cuzco theft, 280 jewel-encrusted items of gold and silver were stolen from an isolated 16th-century church in Apurimac, a neighboring area of the southern Andes. In Lima, airport customs officials frustrated an attempt to smuggle out more than 150 pre-Inca weavings, sculptures and gold masks.

Such cases raise questions about Peru's ability to protect its heritage.

''There is an abundance of cultural richness in this country that is being lost because of inadequate security,'' Ms. Remy said. ''It is very difficult to guard because all of Peru is one enormous archaeological field.''

Many paintings have been stolen from churches by thieves who simply cut them out of their frames.

''These little churches in the villages have incredible treasures in paintings and in gold objects and are completely unprotected, with nothing for security,'' she said. ''They are very easy to rob.''

Araoz said Peru has too little money and too much that must be done with it: ''We have health problems, housing problems, nutrition problems, transportation problems. These are huge questions that require the government's attention.''

So far this year, thieves have stolen at least 20 paintings from churches in Cuzco and the surrounding area.

In May, two paintings disappeared from the colonial Jesuit church on Cuzco's main plaza. Police believe the robbers hid in the church overnight and escaped when it opened in the morning.

Isolated pre-Columbian ruins are plundered by grave robbers known as ''huaqueros,'' from ''huaca,'' the Quechua name for the burial mounds and temples that dot much of the landscape.

''These so-called 'huaqueros' are people from the area who know where things are and go plundering,'' Ms. Remy said. ''They have robbed much of our cultural heritage that way.''

Peruvian archaeologists say the Cuzco theft was the worst since a famous ''tumi,'' or jeweled ceremonial knife, was stolen 12 years ago from Mrs. Remy's museum in Lima.

The tumi was recovered, but the thieves had hacked it to pieces.