An Italian court has sentenced a Romanian man to 20 years in prison for human trafficking after a Guardian investigation revealed that thousands of women from Romania were being raped and used as forced labour on farms in Sicily.

In what investigators claim is Italy’s first conviction for labour trafficking of European citizens, Lucian Milea, 41, was convicted last week of running a trafficking ring that recruited dozens of women in Romania who were then forced into exploitation and prostitution on farms in Ragusa, Sicily.

Ragusa is one of Italy’s biggest producers of fruit and vegetables, which are exported to countries across the EU including the UK.

A court heard that the women were forced to live in terrible conditions in outbuildings on farms without heating, were not paid for their manual labour, were given rotten food to eat, and were beaten and forced to have sex with their employers and other men.

Two Romanian women were sentenced alongside Milea for aiding and abetting underage prostitution. The trial of another three Romanian nationals charged with human trafficking is ongoing.

Twelve women who were trafficked from Romania to Italy assisted police with their investigations. Their lawyer, Liliana Battaglia, commended their bravery and said the case had exposed modern slavery at the heart of Italy’s agricultural production.

“Women were persuaded to move to Italy with the promise of a decent job and shared living space with fellow Romanians,” she said. “When they arrived here in Ragusa and then learned that they had been deceived, it was too late. They were forced to work every day and to prostitute themselves. They were raped by members of the gang, and everything they earned went to their torturers. They were enslaved, in the true sense of the word.”

Lina Trovato, the prosecutor in Catania who led the investigation, told the Guardian: “The thing that struck me most was that these women were not even aware of the dire conditions they were forced to live in. It is a typical element in these types of crimes. People don’t even know they have rights and don’t even realise they are victims of an injustice.”

Police say the investigation that led to Milea’s arrest and conviction was instigated after the Guardian revealed in March 2017 that up to 5,000 Romanian women were being exploited and abused on farms in Ragusa.

Multiple women told the Guardian that they had been forced to have sex with farm owners, threatened with guns and made to work 12-hour shifts in the fields in extreme heat with no water, where they were subjected to sexual harassment and threats. They also complained of non-payment of wages and being forced to live in degrading and unsanitary conditions in isolated outbuildings.

The Guardian investigation also found that there had been a dramatic rise in the number of Romanian women seeking abortions in Sicily. Romanian women make up 4% of the female population in the province of Ragusa but according to the local health authority account for 20% of all registered abortions. Medical professionals treating Romanian women seeking abortions told the Guardian they believed this was linked to systemic sexual exploitation.

After the investigation was published, a delegation of Romanian ministers travelled to Sicily to meet local politicians and the Romanian government agreed to collaborate with Italian authorities to try to stop the abuse.

In September 2017 the police commissioner of Ragusa, Antonino Ciavola, set up a taskforce to investigate the abuse of migrant workers on farms in Ragusa. A series of police raids found hundreds of migrants, including Romanian women, being exploited. A year later the police made a series of arrests and said they had found an organised human-trafficking ring operating between Romania and Italy.

“We found that women were being recruited in Romania and promised good job opportunities in Sicily. But they all ended up as slaves,” Ciavola told the Guardian at the time of the arrests. “It’s hard to imagine how one human being is capable of doing this to another. We have to stop this, and we need to free these women.”

Massimo Scribano, the president of Proxima, an NGO that safeguards victims of violence and labour exploitation in Sicily, said the convictions were a landmark moment in the battle to end labour exploitation in Italy’s agricultural sector. “We are very satisfied with this verdict,” he said. “We have been reporting these crimes against women for years. Perhaps now the time has come to investigate businesses that have been complicit in benefiting from the work of these women who have been forced into slavery.”

Italian exports of fresh fruit and vegetables are worth €366m a year. Much of this produce is grown on the 5,000 farms across the province of Ragusa.

The number of Romanian women travelling to work in Sicily has increased dramatically over the past decade. According to official figures, 36 Romanian women were working in the Ragusa province in 2006; in recent years the number has reached more than 5,000.

“For several years there has been constant movement of migrants toward Italian and European borders. They are leaving their countries of origin because of conflict, sociopolitical unrest, and lack of economic opportunity,” said Giuseppe Giliberti, a deputy police commissioner.

“Economic refugees and migrants are particularly vulnerable to exploitation and human trafficking. Those who have no access to international protection are often trapped in exploitative situations.”

No Italians or Italian businesses are involved in the current prosecutions. Investigations are still ongoing.