Nigeria has secured a major legal victory in the long-running dispute over the Mambilla Hydroelectric Power Project, with an International Arbitration Tribunal dismissing claims by Sunrise Power and Transmission Company Limited that could have exposed the country to more than $3.38 billion.
The ruling, issued on September 17, 2026, brings an end to a nearly nine-year arbitration battle and removes a major legal obstacle that had contributed to delays surrounding the proposed 1,500MW hydropower project in Taraba State.
President Bola Tinubu confirmed the development in a State House statement, saying the International Chamber of Commerce (ICC) arbitration tribunal in Paris ruled in Nigeria’s favour and rejected Sunrise Power’s claims.
“Today’s ICC ruling clears the single biggest legal hurdle that has paralysed the Mambilla hydropower project for years,” Tinubu said.
The dispute dates back to October 10, 2017, when Sunrise commenced arbitration proceedings against Nigeria over an alleged breach of a 2003 agreement relating to the development of the Mambilla project.
According to the Presidency, Sunrise had demanded $680 million in the latest arbitration, while a related claim involving the project sought more than $2.7 billion in compensation and interest.
Together, the two claims placed Nigeria’s potential exposure at more than $3.38 billion.
The three-member tribunal dismissed Sunrise’s claim that Nigeria had breached its contractual obligations under a settlement agreement and an addendum entered into by the parties.
It also rejected the company’s request for an order compelling Nigeria to pay $400 million, comprising a $200 million settlement sum and another $200 million claimed as a default payment.
The tribunal further ruled that Sunrise promoter, Leno Adesanya, was bound by the arbitration agreement with Nigeria under the settlement agreement and addendum. It consequently held that it had jurisdiction over Nigeria’s counterclaim against Adesanya and Sunrise.
As part of the award, Sunrise and Adesanya were ordered to reimburse Nigeria for 75 per cent of the legal fees and expenses incurred in defending the arbitration.
Nigeria’s legal expenses were put at $11.82 million, with $2.5 million expected to be covered from funds held in escrow by the ICC and released following notification of the final award.
The outstanding $9.32 million is to be paid by Sunrise and Adesanya, together with interest at an annual rate of 10 per cent, compounded annually, from notification of the final award until full payment.
The arbitration costs were fixed at $1.66 million, with Sunrise and Adesanya responsible for 75 per cent and Nigeria for the remaining 25 per cent.
The tribunal was chaired by Melaine van Leeuwen, with Stavros Brekoulakis and Simon Nesbitt serving as co-arbitrators.
Nigeria’s legal team was led by Elizabeth Oger-Gross and Tolu Obamuroh of Paul Hastings LLP.
Tinubu commended the Attorney-General of the Federation and Minister of Justice, Lateef Fagbemi, officials of the Federal Ministry of Justice and Nigeria’s legal team for their handling of the dispute.
He also acknowledged former President Olusegun Obasanjo and the late former President Muhammadu Buhari, who testified in Nigeria’s defence during the proceedings.
The President also commended former ministers Babatunde Fashola and Suleiman Adamu, as well as experts, the National Security Adviser and the Economic and Financial Crimes Commission for their roles in the case.
Mambilla Project Rescoped
The Mambilla project has its roots in a 2003 agreement for the construction of a 3,050MW hydroelectric plant in Taraba State under a build-operate-transfer arrangement.
The project was subsequently revised as successive administrations sought to make it financially viable.
In February 2021, the Federal Government announced that the planned capacity had been reduced by about 50 per cent, from 3,050MW to approximately 1,525MW, with the aim of reducing costs by about $1 billion.
The project was later rescoped to about 1,500MW to make it more financially viable and “bankable” for lenders.
The original project was estimated to cost between $5 billion and $5.8 billion, while the rescoped 1,500MW-1,525MW project was reported at approximately $4 billion.
Despite being identified by successive administrations as a major component of Nigeria’s efforts to expand electricity generation, the Mambilla project has remained largely on the drawing board.
Legal disputes, financing difficulties and changes to its implementation arrangements have contributed to the prolonged delay.
A Federal Ministry of Power implementation document previously identified the arbitration, completion of financing arrangements with the Export-Import Bank of China and the need to rescope the project among the challenges affecting its execution.
The latest arbitration ruling therefore removes one of the major legal uncertainties surrounding the project, although financing and implementation arrangements will still have to be addressed before construction can advance.
Tinubu said the Federal Government remained committed to working with genuine investors and honouring legitimate contractual obligations while defending Nigeria against claims it considers unjustified.
The arbitration victory comes amid broader efforts by Nigeria to defend itself against major international claims arising from disputed government contracts.
The Mambilla project remains one of Nigeria’s most ambitious planned hydropower developments, and its progress will depend on resolving the remaining financing, contractual and implementation challenges following the latest legal victory.