The Competition and Consumer Protection Commission and Brokers Ireland have engaged in a highly unusual and bitter war of words over the outcome of a probe by the competition watchdog into the car insurance market published last year.

The five-year long investigation into alleged "price signalling" in the motor market led six motor insurance companies to sign legally binding agreements to reform their internal competition law compliance programmes.

Price-signalling is an anti-competitive practice where businesses make their competitors aware that they intend hiking prices.

However, all six denied involvement in a breach of competition law and there was no finding of liability.

A seventh body, Brokers Ireland, which was also the subject of the probe, declined to sign up to the agreements.

It strongly rejected it ever engaged in conduct that amounted to a breach of competition law.

This morning the CCPC published its full report on the matter, which outlines its reasoning for opening the investigation, the behaviours which came to light and the steps taken to secure the commitments.

Today's report once again refers to the CCPC's comments in August that it regrets Brokers Ireland's refusal to commit to the internal reforms to address the CCPC's preliminary concerns.

Brian McHugh, the member of the Commission with responsibility for Competition Enforcement and Mergers, said "that this arguably calls into question the importance the organisation puts on demonstrating compliance with competition law."

But in a stinging attack on the CCPC, Brokers Ireland accused it of "spiteful commentary intended to blacken and sully the reputation of an organisation that had the courage to stand up to it."

Brokers Ireland said it rejected "unreasonable and unwarranted compliance demands" on the basis that no anti-competitive practices were proven against it.

The body representing hundreds of brokers in Ireland has instead published what it describes as its own report on the investigation, that takes issue with large swathes of the CCPC investigation.

"The approach by which this investigation was conducted by the CCPC was inconsistent, lacked transparency and due process," claimed Diarmuid Kelly, Brokers Ireland Chief Executive.

He claimed that the competition authority is well aware that Brokers Ireland already has in place a robust compliance regime.

The six firms that signed up to the legal commitments in August were AIG Europe SA, Allianz PLC, AXA Insurance DAC, Aviva Insurance Ireland DAC, FBD Insurance PLC and AA Ireland Limited.

The period that the investigation focused on was 21 months between 2015 and 2016.

The probe's preliminary findings alleged that the Irish Brokers Association, which was later subsumed into Brokers Ireland, was involved in making public announcements about industry-wide premium trends, engaging in bilateral discussions with an insurer on private motor insurance premium increases and facilitating contacts between a number of insurers to discuss such increases.