A Department of Justice official and four Chinese students who were arrested as part of an investigation into alleged immigration irregularities may face corruption charges.
The civil servant at the centre of the investigation has been suspended from his post in the Garda National Immigration Bureau in Burgh Quay in Dublin.
The man and four Chinese nationals were arrested last Thursday and released after questioning.
Garda sources said a file on the matter would now be sent to the Director of Public Prosecutions.
The Chinese nationals, aged in their 20s and 30s, were all students of English colleges in Dublin. Gardaí believe some of them were connected with management of the colleges.
Chinese students in Ireland require letters from colleges verifying their attendance records before they can have their certificates of registration issued or annually renewed by Garda National Immigration Bureau officials. These certificates, which are issued as laminated wallet-size cards with photographs, show that the non-national holders have registered with gardaí as required under immigration law.
Gardai say last Thursday's arrests were in connection with alleged irregularities in college attendance records used to have the certificates issued or renewed.
It is understood that a substantial number of registration cards may have been invalidly issued or updated. Gardaí say they expect that this situation will have to be regularised.
Certificates of registration are separate from visas, which also must be updated regularly. Future Garda investigations in the area are expected to include language schools.
This is due to suspicions of collusion between the schools and "agents" handling the irregular registration of students, sources said yesterday.
Several other Chinese nationals were also arrested last Thursday in Dublin following Garda searches in premises including an internet cafe.
Several of these people were arrested for not having immigration documents, while one had a false stamp on his passport.
They were also subsequently released the same day.