The SDU conducted searches at three locations and have removed an amount of material for examination.
Gardaí said the man is being questioned in relation to “possession of fraudulent documentation”.
A Garda statement said: “As part of ongoing investigations targeting the possession of fraudulent documents, gardai from the Special Detective Unit in conjunction with the London Metropolitan Police searched a number of properties in the Dublin area.”
“One man in his 40s was arrested in connection with the investigation and is currently in a north city garda station under the provisions of Section 4 - Criminal Justice Act 1984 for an offence under Section 6 – Criminal Justice (Terrorist Offences) (Amendment) Act 2015.”
Read more: Irish Examiner
