Firefighters have spent nearly five hours battling to control a blaze inside one of Victoria's largest power stations.

Fire Rescue Victoria crews were called to the Yallourn Power Station, in the Latrobe Valley, just before midday after a Triple Zero caller reported burning embers in a coal bunker as a result of a lightning strike.

Firefighters arrived to find the fire about 40 metres by 20 metres high.

About 70 firefighters, 10 firetrucks and two waterbombing aircrafts spent hours trying to contain the blaze, which was deemed under control just before 5pm.

Peter Marshall, from the United Firefighters Union, said earlier he was unsure how firefighters would control the fire.

"What we have here is a critical crisis in the fire service, where firefighters' morale is so depleted, because the government have deserted them," he said on 3AW.

Ambulance Victoria was called as a precaution.

In a statement, EnergyAustralia confirmed a "severe storm" sparked lightning that hit the Yallourn power station and mine.

"The area was investigated immediately after and embers and hot spot smoulders were identified in the Raw Coal Bunker building," an EnergyAustralia spokesperson said.

"No significant damage has been detected however as per emergency protocols Fire Rescue Victoria and our on-site emergency response team responded.

"No-one has been injured and WorkSafe was also immediately notified following the incident.  

"There has been no impact to generation at Yallourn."

Firefighters will remain on scene to ensure the safety of the area.

The coal-fired power station supplies 22 per cent of Victoria's power.

The site, which has been running for more than 100 years, is due to close in 2028 as part of a $5 billion transformation into a "low-carbon emissions hub" by owners EnergyAustralia.

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