Arizona fights huge fire

A state of emergency has been declared

Firefighters in the US state of Arizona have been unable to contain a huge blaze near the city of Tucson, the state's second largest.

The Aspen fire, as it is called, has destroyed hundreds of homes and forced about 1,000 people to flee since it broke out on Tuesday.

High winds have both spread the fire and ground firefighting aircraft - leaving the fire officially "zero percent contained".

The blaze, described by a local fire chief as the worst emergency the area has ever seen, is now threatening a major space observatory.

"We've never seen several hundred homes destroyed in any type of incident - floods, earthquakes, any type of emergency," district fire chief George Good told the AFP news agency.

Unable to fly emergency aircraft, firefighters have been digging trenches to try to form firebreaks around locations such as the town of Summerhaven.

They are working to protect the multi-million dollar Mount Bigelow Observatory by keeping vegetation damp and clearing dry brush from the area.

Officials hope that land burned in an even bigger fire last year will also help contain the Aspen blaze.

State Governor Janet Napolitano has declared a state of emergency and Arizona is designing a programme to transfer firefighters around the state.

But the Aspen fire is only one of eight the state is fighting.

More than half the serious wildland fires in the US at the moment are in Arizona, which has a hot, dry climate.