The victims, who were all Vietnamese, died of suffocation because there was no ventilation in the container.
In the British part of the investigation, five suspects had been arrested earlier, and appeared in court in April. The truck driver, a 25-year-old man from Northern Ireland, already pleaded guilty to manslaughter at a trial in London, reports De Morgen.
In the meantime, the suspected organiser, a 40-year-old man, of the human smuggling operation has also been arrested in Ireland. The British court has already requested for him to be transferred.
In Belgium, the investigation focussed on the organisation of the transports. On Tuesday morning, 13 people who are suspected of having brought the migrants from Brussels to northern France where they could be placed in the trucks, were arrested during different searches, reports De Standaard.
Some Brussels residents of Vietnamese origin were also arrested on suspicion of involvement in the smuggling gang. They are said to have been responsible for the safehouses where the migrants in transit were temporarily housed.
Some suspects have already been arrested by the Bruges investigating judge.