DUBLIN (Reuters) - One of the two Northern Irish men charged with manslaughter over the deaths of 39 Vietnamese people found in the back of a truck near London last month challenged attempts to extradite him to Britain in an Irish court on Thursday.

Britain began extradition proceedings on Nov. 1, a week after the discovery of the bodies in an industrial estate. Eamonn Harrison, 22, was charged with human trafficking and immigration offences, as well as 39 offences of manslaughter.

The UK authorities, citing signed documentation and CCTV footage, allege that Harrison delivered the trailer in which the people were found to a Belgian port before its onward journey to Britain, Ronan Kennedy, a lawyer for the Irish state said.

Harrison’s lawyer, Siobhan Stack, raised a number of issues with the extradition warrant, in particular the “sparseness of the facts” contained within it that she said gave no information as to where the deaths occurred and what Harrison’s involvement was.

Judge Donald Binchy said the matters raised definitely required additional information from British prosecutors before a hearing date that he set for Dec. 12.

The man who drove the lorry to the industrial estate, also from Northern Ireland, was charged last month with 39 counts of manslaughter, conspiracy to traffic people, and money laundering. He is due to enter a plea next week.

Two other Northern Irish men are also wanted on suspicion of manslaughter and human trafficking, while eight people were also arrested earlier this month by Vietnamese police, bringing the total number of arrests there to 10.

The bodies were found in the early hours of Oct. 23 after the container arrived from Zeebrugge in Belgium. The container was picked up at Purfleet dock, east of London and a British court heard this month that a global ring was involved.

Judge Binchy said one of the questions prosecutors needed to answer was the degree to which Harrison was involved in the conspiracy. They also have to make clear whether they plan to prosecute on the grounds of an extraterritorial offence.

Harrison’s lawyer also said the warrant stated that he was a British citizen but that her client was travelling under an Irish passport as an Irish citizen, and that this will be critical in terms of the territorial jurisdiction of the case.

People born in British-run Northern Ireland are entitled to both British and Irish passports.

On setting the hearing date, Binchy also said that the issue of Brexit loomed large with all extradition proceedings to the United Kingdom and that he was doing his utmost to clear all requests by the end of the year.