Construction workers are today holding a series of demonstrations outside the Department of Education in Dublin.

Members of the SIPTU and BATU unions claim the Department is allowing building firms to sub-contract work to other firms who pay below below the minimum wage.

The issue was raised in the Dáil during Leaders' Questions this lunchtime, when Fianna Fáil's Robert Troy raised a whistleblower's claims about sub-contractors working on one site in Dublin.

Education minister Ruairi Quinn said his Department was investigating.