The Civil Registration Service investigated 41 weddings last year as suspected “marriages of convenience”, with 20 ceremonies ultimately prevented from proceeding.
Figures from the Department of Employment Affairs and Social Protection showed 41 cases were referred for investigation, although 11 of those marriages were allowed to go ahead following review, and 10 are still being probed.
The cases involved marriages of non-Irish citizens with non-EU citizens.
The department said Civil Registration Acts require that a couple getting married must give notification in person of their intention to marry to a registrar at least three months before the intended date.
Under the Civil Registration (Amendment) Act 2014, the registrar has the right to investigate and decide whether an intended marriage would be a marriage of convenience for immigration purposes.
According to a department spokesperson: “Marriages of this nature have been used as a means of circumventing national and EU immigration controls in many jurisdictions.
"A registrar may also receive objections to a proposed marriage where a marriage of convenience is suspected.
“The Department of Justice and Equality and the Garda National Immigration Bureau must also be informed of the facts of a case where there is a suspicion that a marriage of convenience is intended.”
Notifications to marry can also be cancelled, abandoned or withdrawn following engagement and/or interviews conducted with a registrar, the spokesperson said.
While the number of notifications to marry and actual marriages between Irish citizens and non-EU citizens has remained consistent over the last five years, the number of notifications and marriages involving non-Irish citizens and non-EU citizens in the same period have plummeted.
In 2014, there were 1,509 notifications of intention to marry received by the Civil Registration Office, and 1,163 marriages registered involving a non-Irish citizen and a non-EU citizen. Last year, just 369 notifications were received, and 234 marriages registered.
A minimum of three months must elapse between the completion of the notification to marry process and the marriage taking place.
Legislation relating to marriages of convenience was introduced following the judgement of the European Court of Justice in the Metock case in 2008.
In its judgment, the court ruled that a non-EU spouse of an EU citizen can move and reside with that citizen in the EU without having previously been lawfully resident in a member state. The judgment does not apply to a non-EU spouse who marries an Irish citizen.
In summer 2015, An Garda Síochána set up Operation Vantage to tackle potentially bogus marriages. Last month, following a day of action to target abuses of immigration legislation and processes around public service licence vehicles, gardaí searched a number of residential properties which resulted in a revocation of 55 immigration permissions.
A Garda spokesman said: “Following these searches, a total of 15 further persons have been identified for investigation where a marriage of convenience and fraud has been uncovered.”