LONDON- The Nigerian government said it had filed a $1.1 billion lawsuit against Royal Dutch Shell and Eni in a commercial court in London on Thursday in relation to a 2011 oilfield deal.

The OPL 245 oilfield is also at the heart of an ongoing corruption trial in Milan in which former and current Shell and Eni officials are on the bench.

Milan prosecutors allege bribes totalling around $1.1 billion were paid to win the licence to explore the field which, because of disputes, has never entered into production.

The new London case also relates to payments made by the companies to get the OPL 245 oilfield licence in 2011.

"It is alleged that purchase monies purportedly paid to the Federal Republic of Nigeria were in fact immediately paid through to a company controlled by Dan Etete, formerly the Nigerian minister of petroleum, and used for, amongst other things, bribes and kickbacks," Nigeria said on Thursday.

"Accordingly, it is alleged that Shell and Eni engaged in bribery and unlawful conspiracy to harm the Federal Republic of Nigeria and that they dishonestly assisted corrupt Nigerian government officials."

The Nigerian attorney general's office did not respond to phone calls and messages seeking comment. Shell said "the 2011 settlement of long-standing legal disputes related to OPL 245 was a fully legal transaction with Eni and the Federal Government of Nigeria, represented by the most senior officials of the relevant ministries."

Eni said in an emailed statement it rejected "any allegation of impropriety or irregularity in connection with this transaction."

"Eni (...) signed a commercial agreement in 2011 for a new licence for OPL 245 with the Federal Government of Nigeria and the Nigerian National Petroleum Company and the consideration for the license was paid directly to the Nigerian government," it said.

Nigeria has already filed a London case against U.S. bank JPMorgan for its role in transferring over $800 million of government funds to Etete, who has been convicted of money laundering. 

In another separate trial, a Milan court in September found a middleman guilty of corruption after prosecutors alleged he had received a mandate from Etete, who has denied any wrongdoing, to find a buyer for OPL 245, collecting $114 million for his services.

(Reporting by Stephen Jewkes, Ron Bousso, Julia Payne, Paul Carsten, Shadia Nasralla; editing by Jason Neely and David Evans) ((Shadia.Nasralla@thomsonreuters.com; +44 207 542 5083; +44 778 99 43141; Reuters Messaging: Reuters Messaging: shadia.nasralla.reuters.com@reuters.net))