Some 300 passengers spent four days blocked inside a rural French airport after a tip-off that the passengers may be the victims of people smugglers.

The Legend Airlines A340 plane was travelling from Fujairah in the United Arab Emirates to Managua, Nicaragua and stopped in Vatry in the Champagne region to refuel.

French authorities are still investigating the aim of the original flight and two passengers have been detained.

Prosecutors wouldn't comment on the nature of the human trafficking allegations or whether the passengers' ultimate destination could have been the US, which has seen a surge in Indians crossing the Mexico-US border this year.

French authorities worked through Christmas Eve and Christmas morning to allow passengers to leave the airfield, regional prosecutor Annick Browne told The Associated Press news agency.

The passengers include a 21-month-old child and 11 unaccompanied minors who were put under special administrative care.

The airport was taken over by police for days, and then turned into a makeshift courtroom Sunday as judges, lawyers and interpreters filled the terminal to carry out emergency hearings to determine next steps.

The plane received permission on Sunday to leave France and was expected to depart Monday, according to an official with the Marne regional administration.

Passengers were seen boarding the plane on Christmas morning.

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Legend Airlines lawyer Liliana Bakayoko said it received approval from French authorities to transport 301 of the 303 passengers on a direct flight to Mumbai, but not all passengers were expected to travel.

Several passengers have requested asylum in France, according to an official with the Marne regional prefecture.

Ms Bakayoko said some other passengers don't want to go to India because they paid for a tourism trip to Nicaragua.

The airline has denied any role in possible human trafficking.

The US government has deemed Nicaragua as failing to meet minimum standards for eliminating human trafficking.

The Central American country has also been used as a route into the US by some migrants because of relaxed or visa-free entry requirements for some countries. Sometimes charter flights are used for the journey.