Police have closed down a circus in southern Italy after a terrified 19-year-old woman was forced to swim in a tank full of piranha fish while her younger sister endured the company of snakes and tarantulas.

Three men have been arrested and charged with holding the Bulgarian women in slavery and breaching international human rights conventions.

The trio, who are accused of running a "circus of horrors", were named as Enrico Raffaele Ingrassia, 57, the owner; his son William Ingrassia, 33; and his son-in-law, Gaetano Belfiore, 25.

The Marino Circus has been offering shows at Petina, south of Naples in southern Italy, in a tent with 200 plastic seats inside.

Mr Ingrassia's daughter, who was not named, told police that a Bulgarian couple and their two daughters, aged 19 and 16, had been held as slaves "in a state of fear" since January.

They were forced to work 15 to 20 hours a day for €100 (£78) a week instead of the promised €480, with €380 deducted as "expenses for their upkeep".

An appalled spectator tipped off the police after seeing the show, in which Giusi, the 19-year-old, tried to escape from the piranha tank "trembling with terror". Her head was held down by Mr Ingrassia.

Her sister, Olga, 16, was bitten by snakes that she was forced to drape on her body, and she had injuries to her stomach where the snakes had wound themselves too tightly around her. The circus owners had rubbed ointment on snake bites on her legs but had refused to take her to a doctor.

Police said that the Bulgarian family had lived in the back of a cockroach-infested lorry used for animal transport. The only meat they had been given since January was in leftovers from the circus owners' Easter lunch last weekend.

Reports said Giusi had a tumour on her ear for which she had twice been operated in Bulgaria. Doctors had told her never to get water in her ears, especially cold water. However the water tank in which she was forced to swim with eight piranhas was kept at a temperature just above zero in order to make the piranhas lethargic.

The Bulgarian family has now been taken to "safe premises". Police said that the raid on the circus followed an undercover operation in which plain clothes officers took their families with them as cover and filmed the show as evidence. The arrested men had appeared surprised, they said, but made no attempt to justify their behaviour.

Corriere della Sera said that the incident appeared to be "something out of the 19th century" but showed that slavery was still "very much a reality" in modern Italy. La Stampa said that the treatment of the Bulgarians was "unfortunately not an isolated incident" of illegal immigrant labour, with many East European women brought to Italy as street prostitutes.

Police said they were investigating "trafficking in humans" by organised crime to supply circuses with cheap labour. The Bulgarian women's mother worked as a cook at the site, while their father moved tents and equipment and cleaned the camper vans and lorries. The mother had once tried to run away but had been captured and beaten, police said.

Livio Togni — a former left-wing senator whose family ran Italy's best-known circus for generations — said: "I've never in my life heard anything like this. There is a strong sense of solidarity in the circus world, and violence is not part of it".

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