Nearly 30,000 firefighters battle US fires

Nearly 30,000 firefighters and support staff are battling blazes across a handful of mainly western US states after millions of acres and multiple buildings have burned.

A total of 7.16 million acres (2.9 million hectares) have gone up in flames across the country this year, the National Interagency Fire Center said.

That's the earliest the 7 million mark has been reached in the past 20 years, it said, adding that a large portion of this was from Alaskan wildfires several months ago.

The firefighters and other personnel, who totalled 28,884 as of Wednesday, were battling large wildfires in 10 states, centre spokeswoman Tina Boehle told AFP.

The northwest quadrant, which is comprised of the states of Washington and Oregon, is the centre's "highest priority," she said.

"The last couple of years have been unusual in the Northwest with reduced precipitation. We've been seeing more fires in the Northwest than usual."

A heatwave exacerbating four years of drought is also making California vulnerable.

A total of 41,194 fires were burning across the United States, Boehle said, adding that as of Tuesday, 1074 structures had been scorched.

"You'll see firefighters from all over assisting with the western wildfires," she said, adding that personnel from the eastern seaboard to Alaska had been tapped.

Canada, meanwhile, has offered up some 100 firefighters plus other personnel and 20 "smokejumpers" who parachute in to fight the blazes.

The centre was also in discussion with Australia to provide assistance, she said.

The 10 states affected by large fires are Oregon, Washington, Idaho, Montana, California, Nevada, North Carolina, Louisiana, Texas and Arizona, Boehle said.