The Department of Labour didn't pay enough attention to allegations of abuse and low pay on chartered foreign-crewed fishing vessels, an internal inquiry has revealed.

One News reports an internal investigation concluded staff were "unable or unwilling" to resolve the problems and lack of action allowed the situation to deteriorate.

The criticism follows the damning royal commission report on the Pike River mine tragedy which found the department didn't ensure safety measures were in place before the explosions that killed 29 men in 2010.

Allegations of physical abuse and very low pay on the foreign crewed ships have been surfacing since 2004.

The department's internal investigation said despite the allegations, owners were not prosecuted because of lack of evidence.