Following a compliance review of its services, Bpost said on Monday it may have been overpaid for the contracts over several years and withdrew its full-year financial guidance.

It said the "impact" of the issue on its 2023 operating profit could be 25-50 million euros ($28-55 million).

"It is self-explanatory to me that every euro overpaid must be refunded. If abuses have occurred, then there will be inevitable consequences," minister for public administration Petra De Sutter said in a statement.

A spokesperson for Bpost declined to comment on the government investigation, but said it would cooperate while continuing its own investigations. The company has given no details on how the potential overcharging might have happened. 

Shares in Bpost, in which the government owns a stake of just over 50%, were down 6.8% at 4.22 euros at 1437 GMT, having earlier touched a record low of 4.086 euros. 

($1 = 0.9025 euros)

(Reporting by Charlotte Van Campenhout; Editing by Mark Potter)