Attorneys representing Metabolife International are denying allegations that the supplement maker lied to the U.S. Food and Drug Administration (FDA) about the negative effects of ephedra. On Thursday, the FDA announced that it had asked the Justice Department to open a criminal investigation into whether Metabolife withheld information about adverse events associated with the supplement.

According to FDA Deputy Commissioner Lester Crawford, the administration has been attempting for several years to gain access to thousands of adverse event reports sent to Metabolife International by ephedra users. The supplement manufacturer has reportedly denied access to the records since 1997. In a move that the FDA called "disingenuous", however, Metabolife agreed to turn over 13,000 health complaints, 80 involving serious side effects, to the administration last week. A spokesperson for Metabolife said the company would also welcome stricter regulation of the dietary supplement industry and would pay up to $500,000 a year to finance an adverse event reporting system.

Although a government safety review on the side effects of ephedra is expected this fall, several leading members of Congress are calling for the immediate ban of the supplement until researchers are sure of the product's safety.