The centre-right Cabinet of Silvio Berlusconi today approved the deployment of 500 troops for three months to take on the Mafia in Caserta, close to Naples, where six African immigrants were gunned down last week.

The Government, which took office in May, deployed 3,000 troops during the summer to patrol alongside police in Italian cities as part of a crackdown on street crime and illegal immigration.

However the latest move marks the first time Italy has used soldiers to fight the Mafia since the 1990s, after the murder in Palermo of two senior anti-Mafia judges, Giovanni Falcone and Paolo Borsellino, in 1992. That operation, codenamed Sicilian Vespers, lasted for six years.

Roberto Maroni, the Interior Minister, said that the three-month deployment to Caserta could be extended. It showed that the state was responding swiftly to the massacre of the immigrants at Castelvolturno in the Caserta area last Friday, he said, adding: "First we dispatched an extra 400 police, now we have taken the decision to deploy the troops".

Ignazio La Russa, the Defence Minister, approved the deployment even though he had earlier said that "Caserta is not Kabul" and that the Italian army "cannot solve all of Italy's problems". Mr Maroni had initially asked for 1,000 troops.

On Monday Italian police began a round up of mafiosi suspected of taking part in the killings that have shocked Italy. Alfonso Cesarano, 29, a convicted mafioso from the Casalesi clan of the Camorra, the Naples Mafia, was arrested at his parents' home in Baia Verde, opposite a games arcade whose owner was shot dead shortly before the attack on the Africans. Investigators believe that the same hitmen were responsible for both attacks, said to be linked to a drugs turf war.

Police said that Cesarano was already serving a house arrest sentence for drugs-related offences. Mr Maroni said that the house-arrest system clearly needed to be reconsidered in cases involving organised crime.

Six Africans — three from Ghana, two from Liberia and one from Togo — were gunned down in the attack, in which 120 Kalashnikov and small-arms bullets were sprayed from cars and scooters. Immigrants went on the rampage after the murders, protesting against the "racist" assumption that all Africans were drug dealers or criminals.

There are an estimated 11,000 to12,000 illegal immigrants in Castelvolturno, but also 2,000 legal immigrants with residence and work permits, many of them second-generation immigrants with Italian nationality. "Racists tell them to go home — but Italy is their home" commented La Repubblica.

Castelvolturno features in the book Gomorra, an exposé of the Camorra by the Naples writer Roberto Saviano, which was made into a prize-winning film. Mr Saviano appealed to the "ordinary people" of the Naples area to break the Mafia code of silence, or omerta, and help police to track down the culprits. He said that the Camorra could only be defeated if local residents stopped turning a blind eye to their activities and rebelled against the "climate of fear".

The violence at Caselvolturno comes after the death ten days ago in Milan of Abdul Salam Guibre, an African-born Italian who was beaten to death by two snack bar owners who caught him stealing biscuits. Thousands of demonstrators marched through Milan last weekend overturning rubbish bins and chanting "Ignorant Italian bastards" while holding up biscuits as a symbol of protest.

Today's Cabinet meeting also approved the construction of ten new detention centres for illegal immigrants, and a measure requiring close relatives of legal immigrants to undergo DNA tests before being allowed into Italy. Mr Maroni said that 23,600 illegal immigrants ("clandestini") had arrived in Italy last year, compared with 14,200 in 2007, an increase of 60 per cent.

Mr Maroni complained that despite a "friendship agreement" at the end of August between Mr Berlusconi and Colonel Muammar Gadaffi of Libya on restricting the flow of illegal immigrants at the tiny Italian island of Lampedusa, off the North African coast, migrants were continuing to arrive. He threatened to block Italian financial aid to Libya, which was part of the August accord, and personally to head a flotilla of coastguard vessels to Libya next month "after Ramadan" to intercept illegal migrant boats.

The Libyan embassy in Rome said in a note that if Mr Maroni arrived "in such a spectacular fashion" he would be stopped. "If we choose to receive him, we will decide when and by what means he will arrive," the note said. Mr Maroni insisted that joint Italian-Libyan sea patrols were part of the "friendship agreement".

Cardinal Angelo Bagnasco, head of the Italian Bishops Conference (CEI), said that the danger of violent racism and xenophobia in Italy was "not to be underestimated". He said that illegal immigrants were "also our brothers. They often pay with their lives in trying to reach Italy's shores". The answer lay in a common EU policy on immigration and economic help for the impoverished countries from which the migrants came, the cardinal said.

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