NEW YORK (CNN/Money) - WorldCom told the Securities and Exchange Commission Monday that it is examining whether there needs to be further restatement of results for 1999 and 2000, possibly expanding the scope of the accounting problems at the telecommunications company.

The SEC filing said that no conclusion has been reached regarding "material reversals of reserve accounts," in those two years. The company restated results for 2001 and the first quarter of 2002 last week due to $3.8 billion in expenses that had improperly been classified as capital expenditures.

Shares of WorldCom (WCOM: Research, Estimates) plunged to 7 cents in pre-market trading Monday, from a close of 83 cents on June 25, the day the accounting problem was revealed in an after-market release from the company. The stock is set to start trading on Nasdaq for the first time since that release Monday.

Former WorldCom CEO Bernard Ebbers

Investigators looking into accounting irregularities at phone service provider WorldCom Inc. are now focusing on former CEO Bernard Ebbers, according to a published report Monday.

Ebbers, who resigned from the company in April, is expected to be questioned by an investigator hired by the long-distance provider he helped build, as well as by the Securities and Exchange Commission and congressional investigators, according to a story in the Wall Street Journal.

The company reported last Tuesday evening that accounting irregularities would cause it to restate $3.8 billion in expenses for 2001 and 2002.

WorldCom Chief Financial Officer Scott Sullivan was fired by the company Tuesday when it revealed the restatement of results. The Journal said that investigators are questioning how Sullivan's actions could have gone undetected by Ebbers, given his tight control of the company.

Ebbers spoke publicly about the accounting problems at WorldCom Sunday at his church in Brookhaven, Miss., his longtime home, the Journal said. It reported that at the end of the Sunday service he spoke to congregation and said, "I want you to know you aren't going to church with a crook."

The paper said that he told the congregation that he had gotten a call about the problems at WorldCom Tuesday.

"I don't know what the situation is with all that has been reported. I don't know what is going to happen or what mistakes have been made," the paper quotes him as saying.

"No one will find me to have knowingly committed fraud," he added.