A Northern Ireland man at the center of a human trafficking operation that left 39 Vietnamese migrants dead in a lorry pleaded guilty to manslaughter at a London court on Friday.

Ronan Hughes, 40, from County Armagh, admitted the charges at the Central Criminal Court, the Old Bailey, having been extradited from the Republic of Ireland in June.

The migrants — ten of them teenagers, including two 15-year-old boys — were found dead in the truck in an industrial zone east of London in October 2019.

They died of a lack of oxygen and overheating in an enclosed space, a coroner's inquest was told.

Hughes had been detained on a European arrest warrant on 39 counts of manslaughter and one count of conspiracy to commit unlawful immigration.

Lawyers for the Irish state told the extradition hearing in Dublin in June that he "organized and controlled the drivers."

The container arrived in England on a ferry from the Belgian port of Zeebrugge.

A number of people have been arrested and charged in Britain, France and Belgium in connection with the case, including the driver of the lorry, Maurice Robinson, also of Northern Ireland.

The 25-year-old from Craigavon pleaded guilty to 39 counts of manslaughter, conspiracy to assist unlawful immigration and acquiring criminal property at a previous hearing in April.

Hughes appeared at Friday's hearing with Eamonn Harrison, 23, from Mayobridge, also Northern Ireland, who was extradited from Ireland in July.

He pleaded not guilty to the same charges and faces a five-week trial starting on October 5 with three other defendants who have also denied involvement in a people smuggling conspiracy.