Fears of a possible terror attack on Victoria's Latrobe Valley power stations have led the Andrews government to lock up a stash of public documents for the next decade.
The documents were withdrawn from public access within days of the state having learnt it faces a higher risk of blackouts this summer and an increased risk of energy shortfalls over the next decade.
The trove includes technical plans of the Yallourn brown coal power station, which, it is feared, could be used to strike at Victoria's power network.
Yallourn is the second largest power station in Victoria and provides about 22 per cent of the state's power supply and 8 per cent of demand in the national electricity market.
The ageing plant has replaced Hazelwood as the most emissions-intensive power station in Australia, but remains critical to Victoria's energy needs.
The state was warned by the Australian Energy Market Operator in a report on September 5 that this summer it would have low energy reserve levels and a heightened risk of blackouts.
Long summer heatwaves would also strain the state's energy reserves over the next decade, the operator said in its 10-year statement of opportunities report.
The government locked the documents away three days later, on September 8.
The precautionary move was revealed under questioning from Liberal MPs in the upper house this week.
Opposition energy spokesman David Southwick said there would be a call for a full briefing from the government on the decision and any information about a possible terrorist threat to the state's power network.
"If the threat is real the public deserves to know," Mr Southwick said.
"We would hope this is not something the government has done to cover up the potential closure of any more power stations."
It is understood the government has deemed leaving the documents in the public domain an unacceptable terror risk, as an attack on the plant could have serious social and economic consequences.
The large stash of documents "identify critical infrastructure relating to Victoria's brown coal industry and electricity generation", Special Minister of State Gavin Jennings said.
"The records subject to the closure notice document key infrastructure that was not demolished and still operates today."
The documents date between 1930 and 2000 and sit in the Public Record Office Victoria.
They also include historical plans and technical drawings for possible future power stations in the Latrobe Valley, pumped storage hydro schemes and environmental assessment reports following the closure and demolition of the old Yallourn W power plant.
They have been made secret under the Public Records Act.
It is the third time the Andrews government has used the Act to sequester documents from public viewing but just the first time it has done so as a precaution against a possible terror attack.
Under the Act, a future government will assess in 10 years' time whether to release the documents again.
The Yallourn power plant is 43 years old and its owner, Energy Australia, has announced that it intends to close it in 2032.
The story Latrobe Valley power plant plans locked up due to terrorism fears was originally published on The Age.