Police in Naples, Italy have arrested 16 judges and seized assets worth over €1 billion ($1.3 billion) in a huge anti-mafia bust exposing the extent of organized crime's penetration into Italian big business and the state.

The judges were among 47 people arrested under operation Bad Metal, which included the seizure of buildings, cars and property.

The arrests were part of a crackdown on the Fabroccino clan, who are believed to have bribed judges in order to obtain favorable court judgments.

Police have not released the names of the arrested judges, the BBC said.

According to the Financial Times, the 16 were all tax judges suspected of forming a vast web of corruption that involved an illicit trade of court verdicts.

In Italy, organized crime has a suspected turnover of more than €100 billion, with many legitimate businesses either paying protection money to gangs, or the businesses themselves recycling the money gained from drugs and arms smuggling.

It is a signal of transparency . . . With measures like this we can conduct a real and concrete battle against the Mafia's infiltrations and can break that vicious circle which damages the economy and healthy companies, Emma Marcegaglia, head of anti-corruption group Confindustria, told the FT last week.

Monday's operation was the largest against the mafia since 2010, when authorities in Sicily seized €1.5 billion in mafia assets on the island.