Twenty-six people have been arrested in France and Belgium in connection with the deaths of 39 Vietnamese migrants found in the back of a lorry in Essex last year.
The dead, including two 15-year-old boys, were found on an industrial estate about 20 miles east of London in October 2019.
The 26 arrests were made on Wednesday after early-morning raids in France and Belgium as a result of a cross-border investigation supported by Eurojust and Europol.
The individuals are suspected to be members of a major migrant smuggling group, which transported mainly Asian refugees, particularly from Vietnam.
The suspects likely transported up to several dozen people every day for several months, Eurojust said in a statement.
In Belgium, 13 people were arrested after 16 house searches were carried out in Brussels, while a further 13 people were arrested in Paris, France.