The Data Protection Commission (DPC) has raised "serious doubts" over the lawfulness of collecting personal data relating to the Covid-19 Pandemic Unemployment Payment (PUP) at airports.
The Government has been criticised for halting PUP for people engaged in foreign travel but has defended the practice, saying more than 90pc of cases related to recipients who were leaving the country permanently.
Social Protection Minister Heather Humphreys announced a Government U-turn on Wednesday to say PUP won't be stopped for people who are travelling for holidays in green list countries.
The data watchdog has been examining the collection of data from passengers at airports and ports.
Deputy Data Commissioner Graham Doyle said last night that the Department of Social Protection had provided further information on the collection and processing of personal data for the purposes of cancelling the PUP and other social welfare benefits.
He said the department had the responsibility to ensure the eligibility criteria for its welfare schemes were being complied with and that it was a requirement for most of the schemes that the recipients must live in Ireland.
Mr Doyle said the 2005 legislation - which gives powers to social welfare inspectors - states they must have "reasonable grounds to believe there has been a contravention" of the social welfare act to "question and make enquiries of a person who is a passenger".
He said: "The department has confirmed to the DPC that, in respect of certain flights over the last number of months, all of the customers boarding the flight were, and continue to be, asked for their details, including name, address and PPSN.
"The DPC cannot see how this practice of collecting information from all passengers simply on the basis they are travelling to a certain destination conforms with the powers of inspectors under the 2005 Act to act and question (and therefore collect data from) a passenger where they have reasonable grounds to believe there has been a contravention. On that basis, the DPC has serious doubts about the lawfulness of the collection and processing of personal data in this context."
He said the DPC was following up the matter with the department "as this practice continues today".
Last night, the department insisted the checks "have a firm legal basis", telling RTÉ they're "vital in order to combat social welfare fraud and protect taxpayers' money".
The Free Legal Advice Centres (FLAC) also raised concern about the issue, arguing it shows the Department of Social Protection "has been operating a blanket policy of questioning passengers boarding certain flights over the last few months".
FLAC managing solicitor Sinead Lucey said that under the 2005 law allowing inspectors to question passengers they must have "reasonable grounds" to believe there has been some contravention of social welfare law before they may approach someone at the airport and make enquiries.
"The mere presence of a person at the airport is not sufficient grounds for them to be questioned about a social welfare payment," she added.
FLAC chief Eilis Barry said there must be a review of the activities of inspectors at airports to ensure departmental policy properly reflects the limited powers they have.