Estate agents claim they can use gardaí to illegally access the confidential Pulse intelligence system to conduct criminal background checks on potential tenants, a Sunday Tribune investigation has found.

The Data Protection Commissioner has launched a probe into this newspaper's findings after four letting agents indicated that they could ask gardaí to conduct criminal background checks on members of the public. The offices of two letting agents were inspected by the commissioner's office on Friday.

The Sunday Tribune, purporting to be a landlord, contacted eight letting agents and asked whether it would be possible for the company to check with gardaí if potential tenants had criminal records. David Swaine, of Property Partners O'Brien Swaine, said: "The word we got back [from a garda] is that it is possible and they would be willing to do it. But it needed to be pointed out obviously if anyone asked they would really not be meant to be doing that, you know. Effectively, you know, a normal person is not meant to be able to just go to somebody and do a police check. You know, it's not legal to just do a police check on somebody… But he did say [the garda] that yes, it would be possible and he'd do it."

Contacted this weekend, Swaine said that what he had told this newspaper after asking a garda to check its intelligence system "wasn't true. I actually don't know anyone who can do that."

A spokeswoman for Dublinlettings.com also claimed the company could conduct criminal background checks with the assistance of the gardaí: "We have an associate who is ex-garda, detective, and if we need to, we use their services. But we check obviously employer references and previous landlord references. If there is any doubt ? because obviously references can be falsified ? if there is any doubt we can double check in that way, criminal records or whatever." When asked if they could definitely check a person's criminal record, the spokeswoman replied: "Absolutely, yeah."

Correspondence from Dublinlettings.com's solicitor this weekend stated: "We have been instructed to write to you to clarify that neither of our clients have arranged or requested any current or former members of An Garda Síochána or any other public servant to provide any information protected by the Data Protections Acts without the consent of the person to whom such information relates."

The letter added that Dublinlettings.com was inspected on Friday by officers from the Data Protection Commissioner "and no issues of any nature arose and the officers who carried out the inspection informed our clients that they were very satisfied with the manner in which our clients maintain their files and their systems and procedures".

Two other estate agents, Champion Property based in Dublin 4 and Property Partners KBA based in Lucan, indicated they would ask gardaí to conduct illegal background checks on their behalf.

"There's no real way of checking although I do have a friend in the guards and if you have particular concerns who we could, if you have particular concerns, ring and check… I do have a contact in there [the gardaí] that I haven't had to use before but, look, we could certainly, if there's anything dubious about it we can try. And if I hit a wall, I hit a wall," said a spokesman for Champion Property. Contacted this weekend, the spokesman said: "I never have done it so I don't know if I made the call what the answer would be."

When Property Partners KBA was asked if it could ask gardaí to carry out criminal background checks, a spokeswoman said: "We don't usually do that to be honest. But I'm sure it's not a problem to check in with the gardaí in relation to that. I don't imagine that being a problem but we wouldn't do it as standard, if you know what I mean."

When asked if they could definitely check a person's criminal record, she added: "That shouldn't be a problem at all." Contacted this weekend, the company said: "In the event that a landlord requests a background check, the onus is on the potential tenant to get a letter from gardaí saying they have or have not a criminal background. But I have never experienced that happening before."

When contacted initially, all four companies also pointed out that they carry out thorough work and previous landlord reference checks with potential tenants.

The Data Protection Commissioner Billy Hawkes has now launched a probe into the allegations of illegal activity in the sector.

"While the Data Commissioner is reasonably satisfied that those in the letting sector understand that it is illegal to seek criminal records information in relation to prospective tenants, he is nevertheless concerned based on the Sunday Tribune's investigation that such information may be sought and is determined to ensure that such practices if happening are stamped out," said a spokesman. "The Data Protection Commissioner is concerned at any suggestion that criminal record information held by An Garda Síochána may be leaked to third parties for purposes unrelated to the law enforcement purpose for which the gardaí hold that information in trust."

As part of its probe, the commissioner's office carried out "no notice inspections" of two letting agents in Dublin on Friday to check if there was any documentation at the offices relating to gardaí who illegally check its intelligence system on behalf of the companies.

"If information is uncovered revealing that individual gardaí are supplying criminal record information it will be passed to the garda authorities for action. Additionally, prosecutions may be brought against any entity that is seeking and receiving such information from individual gardaí illegally," added the spokesman.

A statement from the garda press office said the garda intelligence system should only be accessed for "official purposes. Garda authorities on being notified of unauthorised access will take appropriate action."