According to local tech publication Techpoint Africa, Flutterwave, the largest startup in Africa by private valuation, was involved in a hack last month.
It left more than 2.9 billion (about $4.2 million) missing from its accounts.
In 63 transactions in early February, unidentified actors transferred the money among 28 accounts, according to documents seen by the publication and examined by TechCrunch.
According to Techpoint Africa, Flutterwave has filed a motion to freeze accounts across 27 financial institutions that had dealings with the missing funds, and police investigations are still ongoing.
Over the weekend, the alleged hack was mentioned in a number of tweets.
While some people complained about frozen accounts that could be connected to the hack, others provided information about it.