Emergency operators listened to terrified Australians "dying over the phone" at the height of the wildfire horror.

More than 4,200 phone calls were made to emergency services dispatch centers as victims across the state pleaded for help.

The sheer volume of calls was staggering, said Emergency Services Telecommunications Authority spokesman Wayne Debernardi.

"We are talking a number of calls this country has just never experienced like that before," he said.

"Our call takers had to listen to people dying on the phone and I am sure that is something that will live with them forever."

Fears were growing last night that another monster fire was building as two major blazes burning close together threatened to merge.

Fire authorities fear the extreme weather forecast for next week could rekindle killer blazes that blasted towns off the map and left at least 181 people dead.

Click here to read more on this story from the Herald Sun.