More than 130 taxi drivers or licence applicants suspected of being in Ireland illegally have been identified in Operation Vantage.
The operation was set up by gardaí to target marriages of convenience or 'sham marriages'.
Fifty-five people have already lost the right to remain here and the State is seeking to deport them.
Another seven people have been found who are unregistered and have no legal permission to be in the country.
The Garda National Immigration Bureau has been investigating so-called ‘sham marriages’ under Operation Vantage for several years.
They began investigating the holders of and applicants for Public Service Vehicle licences who were driving taxis after they noticed a substantial increase in applications from non-Irish nationals.
They identified 134 people holding these licences whose legal status was suspect.
Sixty-four people have been identified as individuals whose status here is now questionable.
These cases have now been forwarded to the Irish Naturalisation and Immigration Service, which either grants them permission to remain or deports them.
However, gardaí have already established that most gained Irish and EU citizenship through a sham marriage in Ireland.
Fifty-five people have had their immigration permission revoked, 25 of whom are now subject to deportation proceedings.
Four have been arrested on foot of deportation orders, two of whom have already been removed from the State.
Following searches in Dublin’s north inner-city and in Lucan yesterday, where 90 gardaí raided ten homes, another 15 people were identified as having been involved in sham marriages.
A further seven unregistered individuals were found to be in the State with no permission.
Gardaí also said that valuable intelligence has been gathered and a large number of documents are being examined.