Judgment has been reserved by the Irish court of appeal in the case brought by a man who has launched a challenge to his extradition to face charges in connection with the deaths of 39 people in a container in Essex.

Eamonn Harrison, 22, from Mayobridge in Co Down, Northern Ireland, is appealing against extradition from the Republic of Ireland to the UK to face charges.

He is wanted on 39 counts of manslaughter as well as charges of conspiracy to assist unlawful immigration and conspiracy to commit human trafficking under the UK’s Modern Slavery Act.

It is alleged he had a role in transporting the trailer in which the bodies of eight Vietnamese women and 31 males – including two 15-year-old boys – were found in an industrial park in Grays, Essex, on October 23 last year.

He is alleged to have delivered the trailer to a Belgian port before it travelled to Britain, where it was collected from the Port of Purfleet, Essex, by Maurice Robinson, 25, from Craigavon, Co Armagh.

Harrison was arrested in Ireland last year on a European Arrest Warrant by detectives from the Irish police’s extradition unit and is fighting his proposed extradition to the UK through the Irish High Court.

The High Court sought further information from UK authorities last year in relation to a number of alleged factual matters in the warrant.

His lawyers have objected to his extradition, saying the original European Arrest Warrant was fundamentally defective in terms of a lack of information in relation to the allegations he faces.

Counsel for Mr Harrison, Siobhan Stack, told the court it is not alleged he placed the migrants in the trailer or that he knew they were there, but it is alleged he delivered the trailer to a port in Belgium before its journey to the UK.

Ms Stack said the High Court judge who ordered his extradition misinterpreted the European Arrest Warrant framework in terms of its mandatory requirements.

Mr Justice Donald Binchy ordered Harrison’s extradition to the UK in January.

Counsel for the Irish Minister for Justice, Ronan Kennedy SC, said it was important to remember that mutual trust and mutual recognition exists between member states in European extradition proceedings.

Mr Kennedy said the deficiencies in the arrest warrant for Mr Harrison are not as marked as Ms Stack claimed.

He said the High Court sought further information from UK authorities last year in relation to a number of alleged factual matters contained in the warrant.

He said it is clear that Mr Justice Binchy engaged in a rigorous analysis of additional information and whether it should be relied on.

He said: “I absolutely accept that there was a discussion before the courts in terms of the conditions for additional information.”

“There was input from the respondent’s side of the house so the judge could decide to what extent he should get additional information.”

Harrison listened to the case by video link from his prison cell. He wore a black T-shirt, grey tracksuit bottoms and glasses.

He was remanded further in custody pending the delivery of the Irish court of appeal’s decision.