The Council of Trade Unions says a Government effort to ensure employers are following employment laws is a pious vote-winning move.
Labour Minister Simon Bridges has released a discussion document on possible ways of ensuring minimum employment rights are being met.
It proposes checking sanctions are working, examining the approach of labour inspectors and improving how breaches are dealt with.
But CTU president Helen Kelly said the document's release is a stunt to win votes.
She said the minister has weakened worker rights by reducing union access to workplaces and changing the Minimum Wage Act to accommodate wayward employers.
Labour Minister Simon Bridges rejects that and said the exploitation of workers, and particularly immigrants, is on the rise, and the discussion document is a step towards a solution.