A new round of inquiry has slammed various aspects of Victoria’s Hazelwood mine, which caught fire and burned for 45 days last year.

The inquiry into the blaze was reopened this year, after claims that some residents of the Latrobe Valley in the state’s east had died due to air pollution.

The latest review found that the fire contributed to increased mortality in the region after the fire, but found that because epidemiology - the study of the determinants of disease - was “not an exact science”.

It also took shots at the plans to remediate the mine if it had not caught fire, which were referred to by one insider as “too silly to explain”.

The report found that given the known health effects of breathing in contaminated air over such an extended period of time, the pollution caused by the mine must have caused some deaths.

“However, because of the imprecise nature of the analysis, it is not possible to attribute any specific death to the mine fire,” the report said.

It also criticised “shortcomings” in the way that government officials engaged kept members of the community informed of the possible health impacts.

“Unfortunately the Department of Health came to a premature view about the possibility of an increase in deaths in the Latrobe Valley due to the mine fire,” the report said.

It called on the department to demonstrate a more “open and engaged approach” to local residents, without being so defensive.

The final stage of second inquiry also focused on plans to rehabilitate the Latrobe Valley's three open cut coal mines, which are the main source of Victoria's power.

The inquiry board was shown a letter from one of the Government's main mine advisors, the Technical Review Board.

In it, board chair JM Galvin told the Resources Department in October that aspects of the rehabilitation plan for the Loy Yang coal mine were '”too silly to waste time explaining”.

He raised concerns about AGL's management of its fire risk.

“The proponent has no intention of reducing the fire fuel load on the northern batters until the final rehabilitation is carried out at the completion of Stage C mining in about a decade's time,” he wrote.

AGL had planned to fill the mine pit with water and create a lake when mining had finished.

But experts at Southern Rural Water said the mine would take over 85 years to fill up.

AGL's lawyer, Juliette Forsyth, claimed it could get to a stable level in just 15 years.

Counsel assisting the inquiry Peter Rozen asked whether the Department of Resources had updated the Yallourn coal mine's rehabilitation plan in 2012.

It was revealed that the mine’s operator, Energy Australia, told the department it too planned to create a lake.

But, it said, there were issues with water access and quality that had not been addressed.

The mining firm called on the department to tell it how its own rehabilitation plan would work. .

There did not appear to be any further correspondence with the mine operator.