PHOENIX -- A government study released on Tuesday links many wildfires in the Arizona-Mexico border region to illegal immigrant activity, a finding that Arizona Senator John McCain said backs up comments he made blaming border crossers for some of the blazes.
The study was carried out by the independent Government Accountability Office, the investigative arm of the Congress, at the request of McCain, an Arizona Republican who ran for president against Barack Obama in 2008.
It found that of 77 human-caused borderland wildfires that were investigated by federal officials from 2006 to 2010, 30 identified illegal border crossers "as a suspected source of ignition."
Investigators found half of those fires were lit to signal for help, provide warmth or cook food, although no explicit purpose was given for the remaining fires, which it noted occurred in areas known for drug smuggling.
It added that fire suppression activities were sometimes reduced at night "because of the perceived threat to firefighters' safety."
The report did not say whether any illegal immigrants had been arrested or prosecuted for starting the blazes.
McCain, who sparked a furor in June by suggesting that illegal immigrants were to blame for some of the wildfires raging near the border, welcomed the report's findings.
"This independent GAO study again confirms what U.S. Forest Service and local officials in Arizona have long known: that some of the fires along the Arizona-Mexico border are caused by people crossing the border illegally," McCain said in a statement.
"The report further found that firefighting activities have sometimes been delayed while waiting for law enforcement escorts as protection from armed smugglers, which could cause fires to grow larger and more damaging," he added.
Among blazes that scorched tinder-dry forests in the Arizona borderlands this year were the Horseshoe Two and Monument fires that together burned more than 400 square miles and destroyed more than 60 homes.
The largest blaze in the state's history, the so-called Wallow Fire, torched more than 800 square miles. Two cousins from southern Arizona, who allegedly left a campfire unattended, were later charged with starting that fire.
The GAO report estimates that the federal government spent $33 million fighting human-caused fires along the Arizona-Mexico border between 2006 and 2010.