Victoria’s integrity watchdogs are not equipped to investigate allegations of union corruption and may need expanded powers to tackle criminality in the construction industry, a state government review says.

The interim report of the review, which the opposition labelled a “farce” that won’t uncover how bikies infiltrated taxpayer-funded major projects, also found workers were reluctant to blow the whistle on alleged misconduct due to fear of reprisals and a confusing complaint system.