The new national boss of the militant CFMEU, Zach Smith, has dug in on its ability to investigate itself even and praised former Victorian branch boss John Setka, on whom many of the allegations centre, as a man of integrity and credibility.

It comes as Victorian Premier Jacinta Allan says it is primarily up to the police, corruption watchdogs and federal government to investigate and clean up alleged criminality by the CFMEU at worksites she oversees.