Garuda Indonesia's CEO will have to leave his post after he was caught allegedly trying to smuggle a classic 1972 Harley-Davidson motorcycle on a flight to the country.

"We will start a process to fire the airline's president director," State-owned Enterprises Minister Erick Thohir said yesterday, naming Mr Ari Askhara by his initials AA.

It is the popular name of Mr Gusti Ngurah Askhara Danadiputra, the national airline's president director or CEO, who was one of 22 people listed on the flight of the newly-procured Airbus jet from Toulouse.

The undeclared Harley Shovelhead and two high-end Brompton folding bikes deprived the country of Customs duties worth between half a billion and 11/2 billion rupiah (S$48,500 and S$146,000), said Finance Minister Sri Mulyani Indrawati.

"We will also look at who else is implicated. This is not only a civil case, it is also criminal," Mr Erick told a media briefing.

The Harley-Davidson bike was transported in parts stored in 15 boxes while the two folding bikes and their accessories were stored in three separate boxes, with no Customs declaration, Dr Sri Mulyani told reporters at the same press conference.

The flight had no cargo listed when it arrived on Sunday at Indonesia's main Soekarno-Hatta International Airport.

Citing an internal audit, Mr Erick said AA last year ordered his subordinates in Europe to look for a classic Harley-Davidson of the 1970s model.

"The purchase (of the motorcycle) was made in April 2019. The money (to pay the seller) was transferred to the personal bank account of Garuda's Amsterdam-based finance manager," said Mr Erick.

Dr Sri Mulyani said a middle-ranking Garuda official had previously come forward to claim the motorcycle as his. But a follow-up investigation revealed that he is not a motorcycle rider. The minister stressed that anyone caught giving false testimony could also be charged and prosecuted.