The Education Minister says so far investigations into alleged "wholesale social welfare fraud" on building sites where contracts were awarded by his Department have not turned up any wrong-doing.

In the Dáil this afternoon, Robert Troy of Fianna Fáil revealed a whistleblower had come to him with claims of social welfare fraud on the building sites.

He says the work is awarded to contractors who are then sub contracting it out to companies that are ignoring basic terms and conditions and who are facilitating welfare fraud.

Ruairi Quinn says so far investigations have turned up nothing.

But Fianna Fáil's Robert Troy says inspectors have not even visited one of the sites concerned.