The company has restated past results twice already this year, making adjustments that reduced its pretax profit by about $7.68bn (£4.9bn) for periods in the years 2000, 2001 and 2002. The company faces both criminal investigations and civil suits.
The US Securities and Exchange Commission received the warning during settlement discussions, a WorldCom statement claimed.
The company said restatements of past earnings will not affect WorldCom's ability to continue providing services or to emerge from bankruptcy in mid-2003.
WorldCom and the SEC have presented to the federal judge overseeing the case a plan for settlement of the SEC's charges against the company. A deal might be announced within a week or two, said the report, released yesterday.