NEW YORK (CNN/Money) - ImClone Systems Inc. learned of the Food and Drug Administration's (FDA) rejection of its cancer drug Erbitux application through an "unsubstantiated rumor" three days before it was formally announced, people familiar with the situation told CNNfn.

The sources said that an FDA employee made an off-the-cuff comment that ImClone might receive a "refusal to file" letter during a meeting with a Bristol-Myers Squibb Co. employee before the government agency formally notified ImClone on Dec. 28.

That led the Bristol-Myers (BMY: down $0.28 to $26.80, Research, Estimates) staff to contact Harlan Waksal, then chief operating officer of ImClone (IMCL: down $0.67 to $7.78, Research, Estimates), on Dec. 25.

The company then convened a conference call on the following day with its lawyers and Bristol-Myers to discuss the rumor and to determine if it could be substantiated, these people said.

Family members and a close friend of former ImClone CEO Samuel Waksal (above) sold ImClone stock less than 48 hours before federal regulators told the company they would not consider approving its experimental cancer drug. (Photo: AP)

Between the time Harlan Waksal knew about the possible FDA action and the time the agency actually notified the company of its action, several Waksal family members and a close friend, celebrity entrepreneur Martha Stewart, sold ImClone stock.

The Wall Street Journal reported that people close to the situation said Stewart left a message for Samuel Waksal, then chief executive of the company, the day she sold her ImClone stock, but Stewart's spokesperson said the trade was made prior to the phone call.

The relatives also said they had no prior knowledge of the FDA action, and ImClone could not be reached for comment.

Harlan Waksal, who took the top helm from his brother three weeks ago, is likely to face a week of grilling from shareholders and lawmakers about whether company executives defrauded investors while enriching themselves and those close to them.

The company has scheduled its annual shareholder meeting for Tuesday, and two days later, Harlan Waksal is set to appear in front of a congressional committee that hopes to find out whether ImClone misled shareholders and if its top executives profited from illegal trading in ImClone shares.  

-- from staff and wire reports