Compass Group's involvement in a United Nations procurement scandal deepened last week as it emerged that the caterer had seen confidential tender documents before winning a contract worth £35.3m.
The UN has written to the catering giant's ESS division demanding to know how it obtained commercially sensitive information about the food and water supply contract in Liberia.
This inquiry is part of a series of investigations into alleged corruption surrounding the awarding of UN contracts to various suppliers.
A spokeswoman for the UN said: "We want to know why ESS did not immediately contact us when they received these documents."
The first document was a draft recommendation by the UN procurement department that ESS be awarded the Liberia contract. The second document analysed the merits of the 12 bidders and the third showed the bid prices submitted by five shortlisted firms.
Compass, which beat 11 other bidders to win the peacekeeping contract, has not yet responded to the UN letter, sent on
11 October.
According to reports in the US media last week, Andy Siewert, a development executive at ESS, received the data from IHC Services, a group that acted as a procurement go-between for the UN.
A Compass spokesman said: "Compass Group takes any questions about business operations seriously. ESS is one of a number of suppliers to the UN that has been co-operating with all the relevant authorities in a wide-ranging investigation."
By Tom Bill