Australia issues top fire alert

The fires in south Victoria were Australia's worst natural disaster

Officials in Australia have issued a new level of "catastrophic" fire warning for the first time, during a heatwave in the south of the country.

The new level of warning, which urges people to evacuate, was created after wildfires killed 173 people in Victoria state earlier this year.

Previously, people had the option of staying behind to fight the flames.

South Australia's fire service has warned people in two northern districts to leave before a fire starts.

Many of the victims in south Victoria are thought to have died trying to defend their homes from the flames.

'Real test'

Tuesday's Catastrophic (Code Red) warning was issued after temperatures were forecast to exceed 40C. A November heatwave is unusual in the state, and several days of high temperatures have left the land extremely vulnerable to fire.

Residents are being strongly urged to leave their homes because of a high risk of death or destruction, though they cannot be forced to evacuate.

"To ensure your survival you should leave tonight or early tomorrow morning, well before a fire starts," South Australia's Country Fire Service said.

Any fires in the North West Pastoral and Flinders districts would be uncontrollable, it said.

"In the next couple of days we are going to see high temperatures, very low humidity and very strong winds," said fire service chief Euan Ferguson.

"This is the first real test for the summer."

An inquiry into February's fires in Victoria found that 113 people were killed sheltering in their houses.

They became known as the Black Saturday bushfires, after the worst day on which 2,000 properties were destroyed in 78 communities.