The Department of Foreign Affairs has said it stands ready to provide consular assistance in the case of an Irishman who has been detained in Iraq.
Joshua Molloy from Co Laois is thought to have been arrested along with two Britons after entering Iraq from Syria.
The Sunday Times has reported that the men were fighting alongside the Kurds in Syria against the so called Islamic State group.
They are believed to have been detained in the Iraqi city of Erbil on Friday.
The British Foreign Office is also working on the case, as two of those arrested are British citizens.
Foreign Affairs Minister Charlie Flanagan is being kept fully informed of developments.