Firefighters in New South Wales are tackling one of the worst days for wildfires in its history.

More than 130 different fires are burning, with 40 uncontained, in what is Australia's most populous state.

The risk in some areas is at its highest level - rated catastrophic. More and more people are being told to leave their homes.

Speaking to The World At One, Joel Kershaw, a spokesman for the New South Wales Rural Fire Service, said: "For the fire crews that are there on the ground, fires are nearly uncontrollable in some areas.

"They fall under the catastrophic rating - we've seen temperatures in excess of 43 degrees [Celsius], coupled with wind speeds of over 100km an hour."