A Pennsylvania man arrested by the FBI Monday allegedly has admitted to packing explosive materials, fuses and a lighter in a suitcase that was checked for a commercial flight at Lehigh Valley International Airport, federal prosecutors say.

The revelations surfaced as Marc Muffley is making an appearance Thursday in federal court in Allentown over charges of possessing an explosive in an airport and possessing or attempting to place an explosive or incendiary device on an aircraft.

U.S. Attorney Jacqueline C. Romero is requesting that the 40-year-old be held without bail.  

In court documents viewed by The Associated Press, prosecutors say Muffley admitted to packing the materials in a suitcase that was destined for an Allegiant Airlines flight to Orlando Monday. He then left the airport, called his girlfriend for a ride and changed his phone number before the FBI tracked him down at his home in Lansford later that evening, they added.

PENNSYLVANIA MAN ARRESTED AFTER ALLEGEDLY ATTEMPTING TO BRING EXPLOSIVE ON FLIGHT 

Pennsylvania man airport

Marc Muffley, 40, was arrested by FBI agents Monday night after he allegedly attempted to bring an explosive device onto an Allegiant Airlines flight from Lehigh Valley International Airport headed to Orlando Sanford International Airport Feb. 27. (FBI)

When staff with Allegiant Airlines checked Muffley's bag earlier that day, TSA agents were alerted to the "presence of suspicious items," an affidavit said. 

TSA agents physically inspected the bag and found a "circular compound, approximately three inches in diameter, wrapped in a wax-like paper and clear plastic wrap hidden in the lining of the baggage," according to court records. 

When multiple FBI agents went to the airport to inspect the object and put it through an X-ray machine, it was determined that the bag contained a "granular type of powder" that is "consistent with a commercial grade firework." 

"This granular powder is suspected to be a mixture of flash powder and the dark granulars that are used in commercial grade fireworks," a court document stated. The bag also allegedly contained "a can of butane, a lighter, a pipe with white powder residue, a wireless drill with cordless batteries and two GFCI outlets taped together with black tape." 

NEW JERSEY MAN ATTEMPTED TO BOARD PLANE WITH HANDGUNS, AR-15, TASER, FAKE US MARSHAL BADGE 

One of the FBI agents also observed that a "quick fuse" and a "hobby fuse" was attached to the object, adding that a hobby fuse burns slower than a quick fuse. 

The explosive device posed a "significant risk" to the aircraft and passengers, according to the FBI agents. 

Pennsylvania man explosive

After staff with Allegiant Airlines checked Muffley's bag, Transportation Safety Administration agents were alerted to the "presence of suspicious items," an affidavit states. (FBI)

Muffley was called to the airport's security desk at 11:40 a.m. over the airport's public address system, but he was seen leaving the airport at 11:45 a.m. 

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A spokesperson for Lehigh Valley International Airport told Fox News that the airport remained open during the investigation. 

The Associated Press contributed to this report.