Two men from the Republic of Ireland have been charged as part of an investigation into alleged human trafficking.
Wayne Sherlock, 39, and Eoin Nowlan, 48, were arrested in Dover, Kent, after 10 migrants were found in a lorry carrying tyres near Ghent in Belgium.
A 64-year-old man from Glasgow and a 30-year-old man from County Antrim were also detained on Thursday.
The 30-year-old man was detained after presenting himself to police in Antrim.
The 64-year-old, who was driving the vehicle, has been remanded in custody while the man from Northern Ireland was released on bail after being questioned by National Crime Agency (NCA) officers.
Mr Sherlock and Mr Nowlan are charged with alleged conspiracy to facilitate illegal immigration, the NCA said.
The pair were remanded in custody following a hearing at Canterbury Magistrates' Court in Kent on Saturday.
The NCA said the migrants, believed to be two adults and eight children, are thought to be from south-east Asia.
Two properties in England and Northern Ireland were also searched by NCA officers, with two suspected firearms seized in the Kent raid.