Authorities said they found 577 pounds of hashish Saturday aboard a Bombardier Challenger 604 that arrived at Silvio Pettirossi International Airport in Luque, Paraguay, after a flight from from Panama. File Photo by Juan Pablo/EPA

ASUNCION, Paraguay, June 1 (UPI) -- Paraguayan authorities are investigating a suspected international drug-trafficking operation after discovering 577 pounds of hashish and cannabis aboard a private jet whose pilot left the country before the drugs were found.

The drugs were valued at approximately $3.6 million, making the case one of Paraguay's largest recent air-related drug seizures.

The tale began at 9:12 p.m. Friday, when a Bombardier Challenger 604 arrived at Silvio Pettirossi International Airport from Panama carrying Estonian pilot Keith Siilats, American co-pilot Jabari Stephen Brown and three American passengers.

The aircraft landed without incident and all occupants left the airport terminal, authorities said.