The Victorian Ombudsman is investigating whether complaints against a Maffra milk transport business, Bulk Liquid Carriers, were properly dealt with by Dairy Food Safety Victoria.
The new development comes as the Environmental Protection Agency kicks off an investigation into a Maffra dairy farm supplying Saputo Dairy Australia.
Both the farming operation and Bulk Liquid Carriers (BLC) share a common ownership investor.
Saputo also regularly uses BLC to transport milk.
In April, The Age revealed allegations that milk tankers belonging to BLC were contaminated with metal fragments and the company was operating without a dairy carrier's licence.
Now, the Victorian Ombudsman has stepped in to look at whether Dairy Food Safety Victoria adequately investigated whistleblowers' complaints.
Several sources told Stock & Land at least four complaints about BLC were made to DFSV.
They say the authority was given photographs allegedly showing contamination in BLC tankers, as well as evidence the company transported milk for Saputo while unlicensed.
Under the Dairy Act, the penalty for carrying milk while unlicensed is $19,826 per offence.
Accepting milk from an unlicensed business attracts the same fine.
On Monday, DFSV said the milk carrier company was free to operate while the investigation was underway.
"All aspects of that complaint are still under active investigation," a DFSV spokesperson said.
"We have no other concerns around food safety at this point in time with the dairy carrier unless there is some new information that whistleblowers are able to provide."
The spokesperson could not give a timeframe for the investigation's completion.
Stock & Land asked Saputo if it had investigated all the allegations.
"As a result of our investigation, BLC resolved a small number of administrative matters to our satisfaction," a spokesperson said.
"Our investigation is complete. There are no food safety risks to any of our products and we consider this matter closed."
Saputo would not say whether those "administrative matters" referred to a dairy carrier's licence.
Victorian shadow agriculture minister Peter Walsh contacted the state's Ombudsman regarding the handling of the allegations.
"As a major dairy exporting nation, it's very important that the integrity of our supply chain is beyond question because we don't want any risk to that," Mr Walsh said.
"Other dairy exporting nations would exploit any bad publicity in the markets, which would put our exports at risk."
Meanwhile, the EPA has confirmed there is an active multi-agency investigation underway at a Maffra farm.
The farming aggregation is one of Saputo Dairy Australia's largest milk suppliers and it's not the first time it has come to the attention of authorities.
An EPA inspection in May 2018 found effluent discharging from the property spilling into a nearby creek, which flows into the Macalister River.
It had been fined for a very similar breach of the Environmental Protection Act earlier the same year.
"I had hoped they would take it as an opportunity to improve their processes for managing effluent," EPA Gippsland manager Stephen Lansdell said at the time.
"Apparently, another reminder is required and they will be fined a further $7929."
An associated farm business was fined another $7929 for allowing 10,000 to 50,000 litres of dairy effluent to leave its Winnindoo site and enter a stormwater drain in July 2017.
Lachlan Wigg, who has a stake in both BLC and the Maffra dairy farm, declined to comment when contacted.