Italian police say they have seized more than €1.6 bn in assets from five Sicilian siblings suspected of links to the mafia, BBC News reports.
The five are thought to have been helped by the criminal group to secure public construction contracts.
Police in the regional capital Palermo say it is one of the largest raids they have ever carried out.
Analysts say Sicily's Cosa Nostra and other mafia groups have expanded their activities during Italy's recession.
Among the assets seized are bank accounts, property and furniture.
The five - three brothers and two sisters - are all in their sixties and seventies. They worked as laborers in the early 1980s but went on to become billionaires, Italian media reported.