ARCHAELOGISTS exploring one of Rome's oldest catacombs have discovered more than 1,000 skeletons dressed in elegant togas.

Experts are thrilled by the find - which dates from about the first century - as it is the first "mass burial" of its kind identified. Mystery surrounds why so many bodies were neatly piled together in the complex network of underground burial chambers, which stretch for miles under the city.

It was the custom then for Rome's upper classes to be burnt not buried, so it is thought the skeletons may be early Christians. Tests are being carried to establish whether they suffered violent death or were victims of an unknown epidemic or natural disaster.

Raffaella Giuliani, chief inspector of the Vatican's Pontifical Commission for Sacred Archaeology, who is overseeing the dig, said: "What we have discovered is very exciting. Usually, two or three bodies were put into holes dug out of the rock in the catacombs. But we have several rooms filled with skeletons.

"The skeletons were dressed in fine robes, many of which had gold thread in them, and they were wrapped in sheets and covered with lime.

"This was quite common with early Christian burials, as it was a form of hygiene, and the corpses were also anointed with balsamic spices. Again, this all shows a great amount of dignity and respect given to the dead."

There are several catacombs beneath Rome dating back 2,000 years and they were used as burial places by early Christians. They were also used as secret places of worship as the pagan Romans persecuted Christians, famously feeding them to lions in the Colosseum.

The discovery was made at the Catacomb of St Peter and Marcellinus on the ancient Via Labicana in the south-east of Rome. Ms Giuliani added: "We are trying to establish whether the skeletons were buried there following some form of epidemic or natural disaster.

"Initial examinations do not appear to show any violent trauma, but we cannot rule this out.

"It is possible they could have been persecuted and killed by the Romans and then buried there by fellow Christians - we just don't know."

Professor Andrew Wallace Hadrill, director of the British School in Rome which specialises in ancient history, added: "The fact that the skeletons were dressed in expensive togas is very unusual and would point to the fact that we are talking about the upper classes of ancient Rome.

"At that time, Rome had a population of one million - it is possible that these people were killed by an illness of which we know nothing about."

It was not until the third century that Christianity was officially recognised as a religion and as such during the Medieval Ages it was customary for pilgrims heading to Rome to stop at catacombs and pray for the souls of these early Christians, many of whom had been killed because of their religion.