Construction giant John Holland says it will investigate claims worker safety has been compromised on a Queensland site as militant unions attack the Federal Government’s national workers’ compensation scheme.

John Holland has been accused of lax safety at its Central Queensland Ports Authority site in Gladstone.

Federal Workplace Minister Joe Hockey says Comcare has a lower incidence of injury rates and higher return to work rate than state-run schemes. Comcare has only recently been opened to the private sector.

It was originally created as the workers’ compensation scheme for public sector organisations, but a High Court ruling in March allowed Optus to enter the scheme. Another 17 private companies with national operations have since joined Comcare.

John Holland says it could save up to $10 million a year under Comcare as a result of not having to work within the disparate state schemes.

The company is also suing the Australian Manufacturers Workers Union (AMWU) for telling employees their safety would be jeopardised under Comcare.

In a letter to John Holland employees in May, AMWU National Secretary David Oliver said risks and hazards in the workplace would increase under Comcare.

John Holland has slapped the AMWU with a Federal Court writ stating the letter had “destabilised” its workforce. A court hearing has been set for July 23.