Sydney, Dec 21 (IANS): Australian authorities on Saturday issued travel warnings asking people to delay their journeys as the current weather conditions threaten to intensify the "catastrophic" bushfire crisis.

"We are asking everybody not to travel on roads anywhere near the vicinity of an active fire unless you absolutely have to," the BBC quoted Gladys Berejiklian, the premier of New South Wales (NSW), as saying here.

The states of NSW and and South Australia are the focus of the travel warnings.

Catastrophic fire warnings were in place across NSW. Three blazes around Sydney were currently burning at an emergency level.

A combination of temperatures above 40 degrees Celsius, low humidity and strong winds have worsened the struggle for the almost 10,000 emergency personnel mobilised to deal with the bushfires in NSW.

"They are the very worst of conditions. Given we have a landscape with so much active fire burning, you have a recipe for very serious concern and a very dangerous day," NSW Rural Fire Services Commissioner Shane Fitzsimmons said.

Two volunteer firefighters died on Thursday as they were tackling a large blaze near Sydney.

Fires have also been ravaging the states of Victoria and South Australia, where two civilians died on Friday.

Since September, Australia's bushfire emergency has killed eight people, destroyed more than 700 houses and scorched millions of hectares.