French prosecutor Rémy Heitz announced on Wednesday the arrests of 26 people in France and Belgium in connection with the deaths of 39 Vietnamese migrants who were found in a refrigerated lorry in Britain last year.
The dead included two 15-year-old boys.
Two men from Northern Ireland were arrested earlier this year in connection with the case.
Maurice Robinson (25) from Co Armagh pleaded guilty to the manslaughter of 39 people and conspiracy to assist unlawful immigration and acquiring criminal property.
Ronan Hughes (40) from Co Monaghan is alleged to have recruited Mr Robinson to drive the trailer in which the 39 migrants died, which was discovered on an industrial estate 32km east of London in October last year.
Mr Heitz said the 26 arrests took place simultaneously in different places in the Paris region and in Belgium, as the result of two distinct investigations.
The first investigation, into human trafficking in an organised gang, assisting illegal residence in an organised gang and association of criminals, was opened on October 14th, 2019, eight days before the deaths occurred.
The second investigation added manslaughter to the charges and was opened on March 2nd, 2020.
“The 13 individuals arrested in France are suspected of participating in a criminal organisation that has lodged and transported several dozen migrants from southeast Asia, particularly Vietnam, on a daily basis for several months,” said the statement from Mr Heitz’s office.
A spokesman said the vast majority of the 13 people detained in France are Vietnamese and French citizens.
The investigation was carried out by officials from the French central office for the repression of illegal immigration and the employment of unauthorised foreigners, known by the acronym OCRIEST.
The investigation was coordinated by Eurojust, with the support of Europol. Investigators from Ireland, Belgium and the UK participated.
Exchanges between regional jurisdictions in Lyon and Lille enabled investigators “to identify the immigration networks that received, lodged and transported the migrants in France before they proceeded to Great Britain, as early as November 2019,” the prosecutor’s statement said.