The embattled scheme was dealt a serious blow on Friday after the Data Protection Commission (DPC) said there was no legal basis to require the PSC to access public services besides welfare.

The data protection watchdog said its development had “proceeded by way of one-off, piece-meal changes to existing social welfare legislation, resulting in a situation where, in our view, the approach to the project from a data protection perspective is lacking in coherence”.

The scheme has come under sharp criticism from opposition politicians, casting doubt on whether the Government – which controls only 54 of 158 seats in the Dáil – can pass legislation to address the privacy concerns.

Willie O’Dea, social protection spokesperson for Fianna Fáil, told the Irish Examiner that “amending legislation like the Taoiseach proposed certainly would not have my support”.

Meanwhile, solicitor Simon McGarr, who has highlighted data concerns with the PSC for some time, told The Irish Times that the PSC as currently constituted may not be compatible with EU rules irrespective of legislation.

He said: “A national parliament can pass a ‘dog’s dinner’ piece of legislation, if it has the votes. But if it’s in breach of EU law it doesn’t make it binding on all the other Government bodies.”

The Department of Employment Affairs and Social Protection has said it is still studying the DPC’s report, which is expected to be published later this week.