The countryside is like a tinderbox and the fire has a life of its own - it cannot be controlled

Dorman McGann US Forest Service

Firefighters had been trying desperately to contain the two blazes and keep them apart, but their fears were realised when winds drove the fires together.

The fireball is now about 50 miles (80 kilometres) across, out of control and raging through paper-dry forests.

The blaze has forced 25,000 people from their homes and is threatening to engulf the town of Show Low.

'Getting bigger'

Carrie Templin of the US Forest Service, which is co-ordinating efforts to contain the blaze, said the area had become a "sea of fire".

"It's one big blaze now and its getting bigger," she said.

The fires - both believed to have been man-made - are burning together in the direction of Show Low, a town 240 kilometres (150 miles) north-east of Phoenix.

Dorman McGann of the Forest Service said: "The countryside is like a tinderbox and the fires have a life of their own and make their own conditions.

"It cannot be controlled and our prime objective is to ensure the safety of residents and firefighters."

Mass evacuations

Show Low's 8,000 residents were evacuated on Saturday as the fire there breached a hastily constructed fire line.

Some homes were saved after being drenched in water and fire retardants

Another 8,000 people have already been forced from their homes in nearby Pinedale, Linden and Clay Springs.

Cartha Icenhower of the US Forest Service said the fire had reached the western part of Show Low, but slowed in intensity on Sunday.

"That has given firefighters a chance to go into the town, douse homes and put out cinders that could spark fires," she said. "Even though the fire is burning out of control, there is still hope for Show Low."

So far:

• 1,560 square km (603 square miles) of land have been burned

• Flames have reached heights of 120 metres (400 feet)

• 225 homes have been destroyed

• 2,000 homes have been saved after being sprayed with water and chemicals

• 2,000 firefighters have joined the battle to stop the fire

Arizona Governor Jane Hull blamed poor forest management for the ferocity of the fire, which began early last week and has become the worst in the state for 90 years.

"I know this country and I have never seen anything like this fire," Ms Hull said.

Mr McGann from the Forestry Service said pine forests had became choked with underbrush because environmentalists had blocked efforts to clear it.

"Every time you try to do a sale for logging of any kind you have the environmentalists slap a lawsuit on them," he said.

Colorado blaze

There are 16 other wildfires burning across the western US.

In Colorado, rain and cooler weather helped firefighters attack the Hayman blaze, 90km (55 miles) south-west of Denver, bringing two-thirds of the two-week-old blaze under control.

But all of Colorado's fires are under a red flag warning, meaning that higher temperatures, low humidity and forecasts of higher winds could easily cause a fire to flare up again.

Land burned in this year's fire season stands at nearly 930,000 hectares (2.3 million acres), more than double the 10-year average of 370,000 hectares (920,000 acres), according to the National Interagency Fire Center.

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