AHMEDABAD, India -- India has launched an investigation into how 303 Indians ended up on a chartered flight that was grounded in France last week because of suspected human trafficking, authorities in the western Indian state of Gujarat said on Wednesday.

Tipped off by an anonymous informant, French authorities on Friday prevented the plane from flying to its listed destination of Nicaragua from a refuelling stopover at Vatry airport in northeastern France. It had taken off from the United Arab Emirates (UAE) with 11 unaccompanied minors among the passengers, 276 of whom returned to India on Tuesday.

Many of the Indians onboard hailed from Gujarat, officials said.

Sanjay Kharat, a senior Gujarat police official, said authorities had obtained the names and addresses of 21 persons from the state who were on the flight, and that investigators were trying to determine who facilitated their travel.

"Our teams have already spoken with some of them ...(or) their family members," he said.

The flight was operated by Romania's Legend Airlines. Its lawyer Liliana Bakayoko declined to name the client who chartered the plane, citing contractual confidentiality.

An official at India's home ministry, speaking on condition of anonymity, told Reuters the registration of the chartered flight and "people operating this entire nexus" had been identified, but declined to elaborate. A ministry spokesperson did not respond to an email seeking further comment.

French authorities placed two of the passengers on "assisted witness" status after investigating them for suspected people smuggling, while another 25 remained in France to apply for asylum. In France, "assisted witness" is an intermediate status between that of a witness and an indicted suspect.

Reuters was not immediately able to speak with any of those who returned to India, with some declining to talk after emerging from Mumbai airport and others hiding their faces with their hands or clothing.

The Indian home ministry official said Indian immigration officials were also being questioned to see if any children had left India unaccompanied.

"All these people landed in (the UAE) at different times, and they congregated to leave on the same plane. They had legal tourist visas to enter Dubai," the official told Reuters.

The plane was held in France a day after the U.S. State Department said it would impose visa restrictions targeting individuals operating charter flights into Nicaragua for migrants heading towards the U.S.-Mexico border.

According to U.S. Customs and Border Protection data, the number of Indians caught trying to enter the United States illegally has tripled over the past three years. U.S. authorities caught 96,917 Indians between October 2022 and September 2023, up from 30,662 three years earlier.