(Bloomberg) -- Nigeria has leveled fresh claims of fraud against a little-known offshore firm that won an $11 billion arbitration award as it ramped up the pressure ahead of one of the biggest London trials to take place next year.

The West African country will try to overturn the penalty by proving that Process & Industrial Developments Ltd. secured a gas-supply contract and the subsequent arbitration victory through bribes and lies. A tribunal granted the company the damages in early 2017 after finding that the government had breached the original agreement. 

P&ID didn’t respond to a request for comment but has repeatedly denied the allegations. It says President Muhammadu Buhari’s government has concocted the claims to avoid its legal obligation to compensate the British Virgin Islands-registered company.

The potentially costly crisis for Nigeria stems from a deal struck in 2010 where the government agreed to provide gas to a plant P&ID proposed to build. Buhari’s administration now argues the project was a “sham” from the outset designed by the company and corrupt public officials to engineer the successful arbitration claim that a tribunal delivered more than five years ago. The government introduced the fraud allegations after a UK judge ruled in August 2019 that P&ID could enforce the award, which has increased with interest from an initial $6.6 billion.

Nigeria discovered late last year that P&ID was “in possession of numerous documents which might be privileged and confidential” to the government, it said in documents prepared for a London court hearing last month.

While the “full details” of how P&ID obtained the documents “remain obscured,” it is to be “inferred” they were provided to the company by a former legal director at the petroleum resources ministry and “other corrupted individuals” acting on behalf of the government, Nigeria claimed.

Granting Nigeria permission to proceed to a full trial, Judge Ross Cranston said in September 2020 the government had established a strong case that the contract was “procured by bribes” and the arbitration was “tainted.” There is “a possibility” that Olasupo Shasore, the state’s lawyer during most of the arbitration, was “corrupted,” he said. Shasore didn’t respond to a request for comment. 

P&ID rejected Cranston’s conclusions in its skeleton argument last month, telling the court that Nigeria’s allegations are “clearly unfounded.” The eight-week fraud trial is scheduled to start in January.

The Nigerian government “keenly awaits the opportunity to present its case before the High Court” and “is confident that justice will finally be served,” a spokesman said by email. 

An image of at least one of the privileged documents was supplied to P&ID by Adetunji Adebayo, a Nigerian businessman active in the oil and gas industry who signed an agreement with the company in 2014 instructing him to facilitate negotiations around a potential settlement during the arbitration, according to the government’s skeleton argument. Adebayo was entitled to up to half of any payout above $1 billion, the court document said.

The company’s co-founder, Brendan Cahill, secured the “silence” of one of his former employees who had offered in 2020 to act as a witness in the trial by entering an agreement that is “contingent on P&ID succeeding in its claim,” Nigeria further alleged last month. Neither Adetunji nor Cahill responded to requests for comment.

Following the most recent London hearing, another London judge ordered P&ID to disclose additional information including WhatsApp and text messages.

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