* Incident occurred after complaint on October 30 flight
* Air France has raised matter with French Foreign Ministry
* Argentina's Foreign Ministry says investigating
The president of Air France-KLM Jean-Marc Janaillac has expressed "indignation" at the detention of members of a flight crew in Argentina and referred the matter to the French Foreign Ministry.
The incident, which occurred in late October, could further test relations after French complaints over the renewed imports of Argentine biodiesel to the European Union and as French shipbuilding company Naval Group negotiates the sale of four ships to the South American country.
France's SNPNC labour union, which represents cabin crew, said the employees were detained over a two-day period after the daughter of a former Argentine justice minister, who was a passenger on the transatlantic flight, filed a complaint.
"Chairman Jean-Marc Janaillac expressed his indignation to the Ministry of Foreign Affairs about the arbitrary detention conditions that the Air France crew were subjected to," Air France-KLM said in a statement on Tuesday.
"Air France has asked the relevant authorities to shed light on this case."
The SNPNC union said the passenger had demanded an upgrade to business class which was refused because the cabin was full. The passenger then sought a different seat, citing a neighbour with a disagreeable attitude.
"They were arrested by police and interrogated under conditions that flouted fundamental rights, before they were incarcerated and later released without explanation," the SNPNC said in a statement on its website.
In a letter to the Argentine Embassy in Paris, the union said the flight crew's purser was separated from colleagues during questioning and held in a room measuring one square metre without food or water under the surveillance of two armed guards.
France's Foreign Ministry has demanded an explanation from the Argentine authorities, a ministry official told Reuters.
A spokeswoman for Argentina's Foreign Ministry said it was investigating the conduct of the airport police with the security ministry.
"If they were excessive in their use of force their superiors will decide what to do," the spokeswoman said.