Australia's top research observatory, which houses telescopes used by scientists from around the world, was damaged by a large wildfire Sunday as hot weather and storms stoked dozens of new blazes.

The Rural Fire Service (RFS) of New South Wales, Australia's most populous state, issued an emergency warning for an out-of-control fire that scorched the Siding Spring Observatory, a remote global research facility.

"This is a large and dangerous bush fire. It is burning in the area around Timor Road near Siding Spring Observatory," the RFS said.

It said two properties in Timor Road had been destroyed and part of the observatory was damaged by fire. The extent of the damage was unclear.

All observatory staff were evacuated before the fire and were safe.

Siding Spring, a mountaintop site in the Warrumbungle Ranges about 500 kilometres (310 miles) north-west of Sydney, houses 10 operating telescopes run by Australian, Polish, British, Korean and American researchers.

Administered by the Australian National University's research school of astronomy and astrophysics, Siding Spring is the nation's major optical and infrared observatory and one of the top facilities of its kind in the world.

A university spokeswoman said all observatory personnel had been confirmed as "safely evacuated and accounted for".

Crews were battling difficult conditions, with temperatures in the area above 40 degrees Celsius (104 Fahrenheit) and hot north-westerly gusts of about 60 kilometres per hour.

The fire was burning across a four-kilometre front, with a strong southerly pushing the flames to the north and northeast as night fell.

A partner observatory at Canberra's Mount Stromlo was destroyed by wildfires in January 2003 that killed four people and razed more than 500 homes.

Five telescopes, residences and more than a dozen buildings were ruined in the Mount Stromlo inferno, forcing the termination of a number of major projects including a digital survey of the Southern Hemisphere's skies.

Large parts of Australia have sweltered under extreme heat in the past week, sparking hundreds of wildfires that have destroyed more than 100 homes.

In the northern state of Queensland trains were halted Sunday due to fears that tracks would buckle under scorching heat that has seen bitumen road surfaces melt in some towns.

The RFS said lightning storms started about 40 new fires overnight in northern NSW. They were being fanned by strong winds but most were in remote areas and not a threat to properties.

By Sunday evening there were 134 fires burning across NSW of which 43 were out of control, according to the RFS.

Wildfires are a common threat in arid Australia, particularly in the hotter months between December and February. The government's Climate Commission has warned that global warming will increase the risk.

Some 173 people were killed and more than 2,000 homes destroyed during the so-called Black Saturday firestorm in 2009, Australia's worst natural disaster of modern times.