Computer discs which appeared to relate to al-Qaeda terrorism and a terrorist training manual were found during a search of a house in County Antrim, a court has been told.
The case came before the High Court in Belfast
Abbas Boutrab, 25, was taken from the house to Maghaberry prison as an illegal immigrant in April.
He was re-arrested on terrorist-related offences on Monday of this week, the High Court in Belfast has been told.
The Police Service of Northern Ireland was granted a further 72 hours to question the Algerian by a County Court judge at Craigavon on Wednesday.
On Thursday, lawyers for Mr Boutrab successfully applied for a judicial review of a police decision not to allow him to have his chosen interpreter present alongside another interpreter during police interviews.
Neil Farrell, for Mr Boutrab, said the translator provided by the police, who had been flown over from London, was said to have provided the meaning of questions to the suspect, rather than literal translations.
Some of this concerned evidence in documents found in the house in Newtownabbey concerning bomb-making equipment and a gun silencer, he said.
But Paul Maguire, for the Police Service of Northern Ireland, contended that this interpreter spoke the same Algerian-French dialect as Mr Boutrab, and that there had been no complaint about the service until Wednesday evening.
He said the allegations against Mr Boutrab were very serious.
Referring to the search of the Newtownabbey house in April he said: "Hundreds of files on computer discs were involved containing thousands of pages of Arabic script.
"These appeared to relate to al-Qaeda terrorism and appeared to be something in the nature of a terrorist training manual."
The police had "considerable reservations" about allowing another person to sit in on interviews of a confidential nature, said Mr Maguire.
Information from the interviews could be released to other people, he said.
Mr Justice Kerr said he would allow Mr Boutrab to apply for a judicial review of the police decision to refuse a second interpreter to be present during police interviews.
However, he refused a request by Mr Farrell that interviews be suspended until the court re-convened on Friday.