Read more: D-Day for Vietnamese rhino poachers
The suspects were held after allegedly trying to smuggle approximately 41kg of rhino horn to Hanoi, Vietnam.
The men were booked on a Qatar flight from Maputo, which made a one-hour scheduled stop at the Johannesburg airport.
The pair were charged with illegal possession of rhino horn and smuggling. More charges may now be added, with the emergence of evidence linking the two suspects to rhino killings in South Africa.
This was confirmed by Hawks spokesperson Hangwani Mulaudzi. It is not clear whether the horns seized from the suspects derived from rhino poached in SA.
At the time of the arrest, police suspected the horns came from rhino in the Kruger National Park and sent them for testing. The results of the tests are not known.
The Vietnamese nationals were arrested after information provided to crime intelligence, suggested they would be travelling with horns concealed in bags.
When the plane made its one-hour stop-over, passengers were asked to exit the flight and proceed to the international departures area, though they had expected to remain in the aircraft.
Authorities sifted through the luggage and a South African Revenue Service detector dog trained to identify rhino horn reacted positively to the two bags belonging to the suspects.
The pair have appeared in Kempton Park Magistrate’s Court on several occasions, with the latest appearance on June 5.
Both suspects are expected to appear in on June 12, when a trial date is expected to be arranged.