Efraim E. Diveroli, the brash young Miami Beach arms dealer who landed a $300 million contract with the Pentagon to buy and ship munitions to Afghanistan only to have it unravel in a sprawling criminal case, was in custody again in Florida on Monday, facing new federal charges.

Mr. Diveroli, 24, was arrested Friday in Brevard County, Fla., and charged with possession of firearms as a convicted felon and with possession of firearms while under indictment for a felony offense.

After a brief appearance at a detention hearing on Monday in Federal District Court in Orlando, he was ordered held without bail in the Orange County Corrections Department.

The two criminal counts appeared to be initial charges intended to detain Mr. Diveroli pending the results of an investigation into a more extensive criminal enterprise.