LONDON -- Six women were rescued from the back of a refrigerated truck in France after one of them called a journalist who alerted police, according to local authorities.

The four Vietnamese and two Iraqi migrants were found in the back of an Ireland-registered truck carrying fruit to Italy, where they had been locked for hours at a temperature of 6°C (42°F), said Laëtitia Francart, the public prosecutor of Villefranche-sur-Saône.

Authorities said the six women wanted to illegally enter the United Kingdom, mistakenly believing the vehicle would take them through the border.

Police said Thursday they believe the driver was not responsible and was cooperating in the investigation.

"The six women were placed in administrative detention for irregular entry into the territory and questioned about their migratory journeys," said Francart. "They exonerated the driver, indicating that they had gotten into the truck thinking of going to England based on the Irish registration."

The six women were released on Thursday with four of them required to leave French territory within 30 days and two authorized to stay and submit asylum applications, she said.

The Villefranche-sur-Saône prosecutor shared in a statement that her officers received two calls on Wednesday afternoon about the incident.

The first caller claimed there were people locked in the back of a truck and later provided a registration plate for the truck.

The second came from the driver who indicated that he had stopped at the Dracé motorway after hearing noises from the back of his truck.

The police said they matched the registration plate of his vehicle to that reported by the other caller. They located the truck and opened its back to find the six women sharing a limited area within the cargo.

The first person to alert the police was BBC's Khue B. Luu, who told the news service that she received a text message and then numerous calls asking for urgent help.

"There are some people who crossed the border from France to England in a refrigerated van," she said the first text read.

Luu, who previously covered the death of 39 Vietnamese migrants who suffocated in a lorry trailer in Essex in 2019, said she maintained contact with the women on the truck until they were free and safe.

Analysts say illegal migration is one of U.K. Prime Minister Rishi Sunak's five key priorities for 2023.

In particular, the Illegal Migration Act 2023, which became law in July, seeks to "prevent and deter unlawful migration, and in particular migration by unsafe and illegal routes, by requiring the removal from the United Kingdom of certain persons who enter or arrive in the United Kingdom in breach of immigration control."

Ibtissem Guenfoud contributed to this report.