In a ruling which will be closely watched by the emerging management liability market, a Milan court has acquitted energy company Eni, its CEO and Royal Dutch Shell on Wednesday in a corruption case revolving around the $1 billion plus acquisition of a Nigerian oilfield a decade ago.

The sentence, read out in court by judge Marco Tremolada, came more than three years after the trial first began and after 74 hearings.

Tremolada said the companies and defendants had been acquitted as there was no case to answer.

The Nigerian government said it was surprised and disappointed by the verdict and would consider whether to appeal once its lawyers had read the written judgment.

“The Federal Republic of Nigeria will continue to hold those responsible for the OPL 245 fraud accountable, not only to ensure the people of Nigeria benefit from this valuable resource, but also to make clear its commitment to rooting out corruption in all of its forms,” said a spokesman for the Nigerian government based in London.

The long-running case revolved around the $1.3 billion purchase by Eni and Shell of the OPL 245 offshore oilfield in Nigeria in 2011 from Malabu Oil and Gas, a company owned by former Nigerian oil minister Dan Etete.

The defendants said the purchase price for OPL 245 was paid into a Nigerian government account and subsequent transfers were beyond their control.

The exploration license for the field, some 150 km (95 miles) off the Niger Delta, has not been revoked but it has not been converted into a mining license and no oil has been produced.

Prosecutors alleged that just under $1.1 billion of the amount paid for the purchase was siphoned off to politicians and middlemen, including Etete, a convicted money launderer who acquired the field in 1998 when he was oil minister under military ruler Sani Abacha.

Prosecutors had called for Eni and Shell to be fined, for a number of past and present managers from both firms, including Eni CEO Claudio Descalzi, to be jailed and for $1.1 billion to be confiscated from the defendants.

The defendants all denied any wrongdoing.