Ireland's top gang boss is copying an Italian Mafia system to traffic drugs and money across international borders.

That’s according to a report following a trans-national investigation which found that Christy Kinahan’s crime empire has set up 200 companies that operate in 20 countries.

The report found Kinahan copied the Italian Mafia’s “golden rule” of using food companies as a front to traffic drugs across borders by taking control of a number of “food wholesalers.”

Kinahan is a convicted drugs dealer who relocated to Spain after being released from prison about 15 years ago.

Since then, from his base on the Costa del Sol and operating through international and Dublin gangs, he has set up a criminal empire stretching across the world from Brazil to Europe.

In the last year his gangs have murdered several associates of a rival group led by members of the Dublin-based Hutch family.

A European Commission-funded report on crime, called "Transcrime," has reported that organized crime in the Irish Republic is worth €1.7 billion ($1.9bn) to a total of 40 gangs, nine of them “primary” operators.

In recent years Irish and Spanish police targeted the Kinahan gang with a series of information exchanges called Operation Shovel.

The Irish Times reports that details emerged piecemeal, but "Transcrime" reveals new detail about the sheer size of Kinahan’s empire and ambition.

“Food-trading companies, bars, and restaurants were set up in Ireland, Spain and the U.K. for laundering and functional purposes,” the report says.

“According to the ministry of the interior, since 2008 officers at the [Spanish] Economic and Fiscal Crime Unit and the Costa del Sol [police] had traced more than 200 trading companies used to channel funds acquired by the group through illegal business deals.

“Real-estate properties were used by the criminals as houses or warehouses in which to stock smuggled goods.

“Moreover, the food import-export company based in Ireland was run by Irish criminals who used the business to transport drugs from Spain to Ireland. Once the drugs had entered Ireland, Irish criminals sold them to criminal gangs nationwide, making significant profits.”

The report said the Kinahan criminal group targeted by Operation Shovel controlled wholesale food traders used to export drugs from Spain to Ireland.

“This is somehow a ‘golden rule’ because also other foreign groups, especially Italian Mafias, rely on food import/export companies to transport heroin and cocaine across countries,” the report added.

Police on scene at scene of the shooting of Martin O'Rourke in Dublin, in April 2016.RollingNews.