A judge in Milan ordered Eni, Shell and key figures such as Eni chief Claudio Descalzi and his predecessor Paolo Scaroni to stand trial in proceedings to begin on March 5th.
The companies are accused of corruption in the 2011 purchase of OPL245, an offshore oil block estimated to hold 9 billion barrels of crude, for $1.3 billion.
"Eni's Board of Directors has reaffirmed its confidence that the company was not involved in alleged corrupt activities in relation to the transaction," the Italian firm said in a statement on Wednesday.
"Eni expresses its full confidence in the judicial process and that the trial will ascertain and confirm the correctness and integrity of its conduct," it said.
It insisted in particular that "chief executive Claudio Descalzi was not involved in the alleged illegal conduct".
Claudio Descalzi. Photo: Eric Piermont/AFP
Both companies are charged with corruption in Nigeria over the accord, which allegedly saw Nigeria's former president Goodluck Jonathan and his oil minister pocket bribes.
The deal saw the Nigerian government act as an intermediary between the oil majors and Malabu Oil and Gas, a Nigerian company allegedly controlled by former petroleum minister Dan Etete.
Allegations of corruption and bribery have mounted in the years since, forcing Shell and Eni to repeatedly maintain that they acquired the rights to the lucrative block in line with Nigerian law.
But email exchanges between Shell management cited in a report by corruption watchdog Global Witness, and seen by AFP, suggest that Shell was aware the money was likely to be funnelled to individuals, including Etete and Jonathan.
Etete was also ordered to stand trial by the Milan court.
Nigeria's anti-graft agency filed corruption charges against Shell and Eni in March, accusing 11 defendants, including Etete, of "official corruption" in connection with the oil block deal.
Jonathan has denied receiving kickbacks, saying in January that he has not been "accused, indicted or charged for corruptly collecting monies" linked to the deal.
The OPL245 oil block has been a source of contention for almost two decades.
In 1998, the block was awarded by then-petroleum minister Dan Etete to Malabu Oil and Gas.
Years of legal wrangling between Malabu, the Nigerian government and Shell ensued, with Shell ultimately winning rights to the block in a partnership with Eni.
Nigerian President Muhammadu Buhari, who has promised to fight corruption in Nigeria's oil sector, has said "mind-boggling" sums have been stolen from the public purse.
By Ella Ide