Swiss caterer Supreme Foodservice plans to serve Compass Group with a writ this week, claiming damages for lost income on UN peacekeeping contracts.
The US lawsuit, which seeks $125m (£72m) in compensation, alleges that Compass division ESS illegally obtained UN business worth more than $350m (£203m) through what it called "rigged bids".
Supreme co-owner Michael Gans said: "After analysing the information, we think there may have been a conspiracy to obtain UN business. We have been damaged by that and want to recover those damages."
The complaint said: "For five years defendants engaged in an illegal scheme involving mail fraud, wire fraud and bribery. It contaminated a bidding process designed to be free and fair."
"ES-KO is a rational company. They have access to all the information and I don't see why they would view it any differently to us," he said.
A Compass spokesman said the company would resolutely defend the complaint and it did not expect it to impact on financial performance.
By Tom Bill
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