A labour hire company is under investigation for being accused of ripping off customers at a QLD abattoir.

Taiwanese workers were supplied to the Greenmountain Food Processing plant at Coominya, west of Brisbane, by labour hire company GOYX Pty Ltd, while they were in Australia on working holiday visas.

Two workers have formally complained to have been underpaid in wages and superannuation, as well as being asked to register an ABN, which could technically make them a contractor.

Unions are now concerned others in the industry may also be at risk.