OTTAWA -- The World Bank benefits from immunity under international law and won't have to hand over documents to a Canadian court hearing a corruption case involving ex-SNC-Lavalin employees, the Supreme Court of Canada ruled Friday.

The international financial institution's refusal to submit to an order signed by a trial judge was addressed by the high court, which found in its favour in a unanimous decision.

Four people -- three former SNC-Lavalin (TSX:SNC) officials and the representative of a Bangladeshi official -- are accused in a case that centres on the granting of a lucrative supervision and advisory contract for the building of a multi-purpose bridge over the Padma River in Bangladesh.

The accused are ex-SNC employees Kevin Wallace, Ramesh Shah and Mohammad Ismail as well as businessman Zulfiquar Bhuiyan.

They'd been seeking information gathered by a division of the World Bank that investigates fraud, collusion and corruption cases. The unit initially shared some of its findings with the RCMP, which led to the federal force laying charges.

The Mounties announced in September 2013 that charges of bribing a foreign official had been filed in Toronto against Wallace and three other men.

The World Bank fought the order and the Supreme Court ruled its initial co-operation in the case did not mean the Integrity Vice Presidency (INT) -- an independent investigative unit within the bank -- had renounced its immunity.

"The World Bank Group's immunities cover the records sought and its personnel, and they have not been waived," the high court ruled. "Moreover, the INT's records were not disclosable under Canadian law."

The Supreme Court found the Ontario Superior Court trial judge had erred in issuing the order.

"He (the trial judge) found that the INT could not selectively share some of the information, documents or correspondences in its possession with Canadian law enforcement officials," Justice Suzanne Cote and Justice Michael Moldaver wrote on behalf of the court in a 70-page ruling.

"However, the doctrine of selective waiver, developed at common law, should not inform the interpretation of an international treaty."

Also that year, the World Bank, which had funded the project, prohibited SNC-Lavalin and hundreds of its subsidiaries from having access to institution-funded projects for the next 10 years.

It was described at the time as the longest exclusionary period ever doled out by the Washington D.C.-based institution.