Newly instated Australian Building and Construction Commission boss Stephen McBurney isn't going any softer on unions than his predecessor Nigel Hadgkiss.

The ABCC -- who got a new boss after it was revealed Hadgkiss had breached the Fair Work Act by misrepresenting the law for over two years -- has clarified a directive, warning employers may not be able to apply for government tenders if their employees display the "logos, mottos or indicia" of unions: