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Questions are mounting over whether the fallout from the Hazelwood coal fire disaster could have been reduced through better management of the mine and more rigorous regulations.

Firefighters said critical equipment, including water mains and sprinklers, had been removed from the disused section of mine, which has been on fire for three weeks.

They also said the mine had not been adequately rehabilitated with a top layer of clay and soil to reduce the risk of fire taking hold.

Moe South CFA captain Brendan Jenkins, who has been fighting the large blaze, said sprinklers and mains had ''clearly been ripped out'' and there had not been thorough rehabilitation.

''If it was properly covered with non-combustible material, clay and vegetation, then it wouldn't have burnt at all,'' he said.

A career firefighter who did not want to be named also said crews were unable to make progress in the northern walls because most of the water mains and sprinkler heads had been removed. ''The main reason we were unable to make any progress in the northern section was because of the water issues. It meant during the early stages of the fire there was no water access to contain it,'' he said.

He said the fire did not take hold in some parts of the mine's northern wall that had been rehabilitated and management was now furiously reinstalling the mains.

A spokesman for mine operator GDF Suez responded that fire services were in place in ''the bulk of the areas impacted''. He said the fire had initially cut power to the mine, reducing water supply and firefighters' ability to battle the blaze for about 12 hours.

The spokesman said the mine plan included ''stringent operating, safety and rehabilitation requirements'', and he blamed arson for the fire that on Friday led to vulnerable people being advised to leave their homes. ''We are alarmed that our business is now threatened with such a serious situation as a result of a reckless act of arson.''

Environmental Defenders Office principal solicitor Felicity Millner said there appeared to be potential compliance issues.

''If [the work plan] hasn't been complied with, it raises serious questions about the department and the role they took in ensuring compliance,'' she said.

''Whether it's a failure of the regulations or enforcement, it needs to be sorted out because it shouldn't have happened in the first place.''

CFMEU mining and energy district president Luke van der Meulen said the fire was in an area that had not been used for three decades, and he believed the firefighting equipment was removed in the 1990s.

He hit out at successive governments and regulatory authorities for allowing the equipment to be removed, before the area was covered in earth. ''Negligence or asleep at the wheel are the terms I believe that apply.''

The Hazelwood mine has previously been marked a ''high-risk'' bushfire site by the CFA, prompting it to create a bushfire mitigation plan in 2012.

There have been several fires at the 3554-hectare site, including in 2006, when a disused section of the mine burnt for more than a week.

The Hazelwood plant and mine were sold to British company International Power when Victoria's energy sector was privatised in 1996.

International Power was delisted in 2012 following a takeover by GDF Suez, which has a market capitalisation of more than $40 billion and is 35 per cent owned by the French government. A GDF subsidiary owns a majority stake in and operates Hazelwood.

Hazelwood employs 540 people and 300 contractors, and supplies up to 25 per cent of Victoria's energy.

A spokeswoman for Energy Minister Nick Kotsiras said GDF Suez had complied with the rehabilitation requirements in its work plan, but would not reveal what those requirements were. A request has been made to access the work plan.

Mr Kotsiras' spokeswoman said the Department of State Development, Business and Innovation regularly reviewed a mine's compliance with its work plans, including visits by mine inspectors.

Under the 1996 mining licence, the operator was obliged to put up a $15 million rehabilitation bond, which is meant to cover the costs of rehabilitating the site entirely after decommissioning.

Environment Victoria acting chief executive Mark Wakeham said the bond was inadequate and questioned whether taxpayers would have to make up the difference.