A man arrested under the Terrorism Offences Act has been released without charge.
The Moroccan man in his 40s had been arrested along with an Algerian man in his 30s who remains in custody.
The arrests followed a number of searches in Swords, Stepaside and the South Circular Road in Dublin - as well as Trim in Co Meath.
The Moroccan man has since been released from custody and a file is being prepared for the DPP.
Two men were arrested yesterday on suspicion of funding Islamic State (IS) as part of a sophisticated operation by specialist Garda terrorism units, writes Cormac O'Keeffe.
Separate Garda sources last night described as “significant” the arrest of the duo — one an Algerian aged in his 30s, and the other a Moroccan aged in his 40s.
They were arrested on suspicion of money laundering to fund international terrorism — the second such operation in under a fortnight.
Sources said the two operations are not connected, although both involve Irish and foreign police and security agencies.
The operation was carried out by the Counter Terrorism International unit, attached to the Special Detective Unit, which combats subversive activity. They were assisted by the Security & Intelligence Section at Garda HQ — the force’s intelligence-gathering agency.
Four searches were conducted as part of the operation. Three were across Dublin: In Stepaside, south county Dublin; Swords, north county Dublin; and South Circular Rd in the south inner city. A fourth search was conducted in Trim, Co Meath.
The men were arrested in Swords and Stepaside.
Gardaí removed digital devices as well as documentation.
They will now be examined to identify sources of money, how it was being laundered, and where it was being sent.
Sources said these operations do not necessarily indicate a rise in IS-related activity, and Garda units act “when the time is right”.
Sources said yesterday’s operation is likely to lead to “further inquiries”.
The two men were detained under section 4 of the Criminal Justice Act and were being held at Blackrock Garda Station.