The oil giant said it was cooperating with the authorities.
The probe is connected to the 2011 $1.3bn purchase of Nigeria’s OPL-245 offshore oil block by Eni and Shell.
As part of the investigation, Shell headquarters in The Hague were searched in February by Dutch police and prosecutors, a spokesman added.
“We can confirm we have received notice of proceedings from the public prosecutor in Italy,” the Shell spokesman said.
In 2014 a Milan court starting probing Italian oil giant Eni over allegations of corruption connected to the OPL-245 offshore oil block acquisition.
Eni has denied wrongdoing, and has said it dealt exclusively with the government of Nigeria, paid fees into a government account and did not use intermediaries for the transaction.
Shell’s spokesman said: “Shell is cooperating with the authorities and is looking into the allegations, which it takes seriously.
“Shell attaches the greatest importance to business integrity, one of our core values,” he added.