The Australian Competition and Consumer Commission (ACCC) will investigate transport giant Toll’s arrangements with the Transport Workers Union (TWU).

Insiders say it is one of the first times the ACCC has taken a look at deals between private companies and trade unions.

Normally, industrial relations agreements would be outside the ACCC’s ambit, but reports claim that this case is different because the agreement itself could be the source of reduced completion.

The case comes from before the recent ACCC decision to allow the TWU to represent around 75 Queensland owner-drivers in negotiations with Toll.

The deal in question sees Toll allegedly paying around $150,000 a year into a union-owned company, about $25,000 of which is dependent on the TWU taking action against Toll competitors.

Claims made at the Trade Union Royal Commission and in media reports say that the agreement saw the union attacking one Toll competitor each year in 2011, 2012 and 2013.

News Corp media outlets claim that Toll would each year agree on the target for a high volume of union audits, wage inspections and compliance investigations. It says the deal has been expanded so that the TWU must make moves against five companies per year.

“The source of this information is none other than evidence given to the Trade Union Royal Commission under oath by Damian James Sloan, Toll’s senior legal counsel, workplace relations and safety,” writes business journalist Robert Gottliebsen, founder of Business Review Weekly Magazine.

“It’s a bizarre arrangement that threatened Australian productivity.,” Mr Gottleibson said.

The ACCC is reportedly investigating whether the Toll deal with the TWU has either substantially lessened competition or is designed to do so.

If the watchdog finds evidence of a breach of trade laws, then the matter will go to the Federal Court, and Toll is expected to vigorously defend its position in the meantime.