AOL last week said that it was investigating the accounting of transactions totalling $49m over six quarters. One of the deals with Worldcom involved "round-tripping" - deals in which a company sells services or assets to another company while buying back similar services or assets from that company simultaneously.
AOL and WorldCom engaged in a round-trip deal where AOL purchased network capacity from WorldCom's UUNet subsidiary, while WorldCom agreed to buy ads on AOL.
Neither company would confirm the report.
AOL declined comment pending the continuation of the company's investigation into the transactions in question, according to Andrew Weinstein, an AOL spokesman.
"WorldCom does not and has not engaged in swap transactions," said Julie Moore, spokeswoman for WorldCom.