NEARLY 70 bogus marriages were stopped from taking place last year as immigrants desperate for residency in Ireland set up sham weddings.

The Department of Justice has been forced to establish a marriage investigation unit because of the enormous rise in suspicious weddings between immigrants and non-nationals.

Figures from the department show that 14 wedding licences were outright refused in 2007 because the "bona fides" of the partnership were under question.

A further 53 applications were abandoned, primarily where preliminary investigations had been carried out and the Irish nationals involved had decided to withdraw from the process.

The department said 30% of people seeking residency in Ireland on the basis of marriage were in Ireland illegally or on a temporary visa.

Immigration authorities suspect that many of these proposed weddings may in fact be "marriages of convenience".

Gardaí said that individuals with mild learning disabilities and people with chronic drug addiction were being targeted in the green card-style scam.

One senior detective said the going rate for such an "arranged marriage" was €3,000 to €4,000, with a smaller deposit paid up front.

Gardaí have also gathered intelligence on EU nationals flying into Ireland, purely for a bogus marriage, only to leave the country days later.

It is believed the upsurge in bogus marriages relates to a controversial Supreme Court decision which removed the automatic right for non-national parents of Irish-born children to remain in Ireland.

One officer said: "That was considered the best route to residency in Ireland but it has been replaced by these show weddings as the first choice."

Wedding applications involving an Irish national and an immigrant, who otherwise wouldn't be allowed stay in the EU, are strictly vetted by immigration authorities. Both parties are interviewed and asked a series of questions to ensure they know each other. If their answers do not match up, the department can then stop the wedding. If it goes ahead, newly married couples are checked to ensure they live together and that they aren't still claiming social welfare as single parents or single persons.

The Department of Justice said: "Marriages of convenience for the purpose of circumventing normal immigration controls are experienced by immigration jurisdictions worldwide.

"The contracting of marriages in order to gain an immigration advantage represents a significant challenge. Marriages of convenience are by their very nature difficult to detect. Final determination as to the validity of marriage-based claims in this area can only be made after an in-depth examination of the particular circumstances of each individual case.