Radio New Zealand - Te Reo Irirangi o Aotearoa

Bush fires in south east Australia have killed at least 14 people in small towns north of Melbourne. It's feared the death toll may pass 40.

More than 100 properties have been lost, as fire crews battle dozens of blazes.

The ABC reports a cool change which promised to bring relief to fire crews on Saturday brought changing winds instead - turning fires from extremely dangerous to deadly.

The deterioration in conditions forced many crews to abandon fighting fire fronts and focus on protecting properties.

Six people are known to have died at Kinglake, north of Melbourne, when fire swept through the entire town.

Four deaths have also been confirmed at Wandong, three at Strathewen and one at Clonbinane.

Firefighters continue to work on 11 major fire fronts across the state.

Dozens of homes have been destroyed but it will be some time before the full extent of the losses is known.

Victoria Police Deputy Commissioner Kieran Walshe says the death toll is almost certain to rise.

"This has been an absolute tragedy for the state and we believe this figure may only get worse," he said.

"We're concerned this figure could even reach up into the 40s."

Victorian Premier John Brumby says it has been a horrific day.

"We have had 14 confirmed deaths. There will be more unfortunately and that number could rise considerably," he said.

"It's been I think the worst day in our history, we've had temperatures across the state of some parts of 48 degrees."

Australia's worst bushfires occured on Ash Wednesday in 1983, when 75 people were killed in Victoria.

Temperatures in Melbourne rose to 46.4 degrees Celsius on Saturday - the highest on record.

Thunderstorms forming

The ABC reports the fires are becoming so big they are creating their own weather.

Senior weather forecaster Terry Ryan says thunderstorms are forming over the fires in parts of west Gippsland.

"We call it pyrocumulus, where all the ash coming out of the fire causes lifting and convection, and can cause a thunderstorm-looking top," he said.

In New South Wales, firefighters are battling more than 40 fires across the state. More extreme weather conditions are forecast for Monday.