The three Libyans and an Algerian arrested by anti-terrorist Gardai on Tuesday have been released without charge.
The four, who were suspected of having links to Osama bin Laden’s al-Qaida organisation, were detained during raids on five premises in Tallaght, Rathmines and Ballinteer.
Cash and computer records were seized during the raids, which followed increased surveillance on at least a dozen people Gardai believe are linked to al-Qaida.
However, there was no evidence against the four men arrested this week and they were released without charge.