Firefighters in the southern Australian state of Victoria were working Saturday to contain about 20 major fires that threatened to merge into one massive blaze.

The fires have burned at least 180,000 hectares of drought-stricken farmland and forest.

This photo released from NASA shows smoke from fires burning in southeastern Australia on Friday.
(NASA Satellite/Associated Press)

There are concerns they could soon merge, sparking fears of a scenario similar to that in 1939, when the Black Friday fires stretched from Alpine National Park to the coast, killing 71 people in Victoria.

Heavy smoke across much of the eastern part of the state set off fire alarms and disrupted flights at Melbourne's main airport on Saturday.

Qantas Airways said two of its flights to Melbourne had to be diverted to other airports because of poor visibility.

People living in more than 20 nearby towns have been warned they may have to leave their homes.

Temperatures reaching nearly 40 C and high winds are driving the fires, which are expected to push toward the coast over the next few days.

Soldiers have been called up to bolster a mostly volunteer firefighting force of almost 3,000, including a contingent from New Zealand.

Typically, Australia's most serious forest fires are reported in December, January and February.

In 2003, brush fires destroyed about 500 homes, blackened three million hectares and killed seven people.