Fires allegedly set by farmers sent clouds of smoke across Argentina's capital on Thursday, disrupting air and highway travel and choking Buenos Aires residents.
Some 270 square miles have burned in recent days, according to Interior Minister Florencio Randazzo.
"We are facing a disaster caused by the hand of man," he said Thursday. "Burning pastures is a crime."
Officials said farmers set the blazes to cheaply clear scrub from grazing land.
President Cristina Fernandez urged authorities to prosecute offenders. "These fires are the result of two aspects of human nature: irresponsibility and irrationality," she said.
The smoke forced air traffic controllers to cancel landings at airports in Buenos Aires and led police to close some major highways. Some bus routes were scrapped for lack of visibility.
Authorities reported a steep increase in the number of people at hospitals with eye problems.
By Thursday afternoon, the smoke drifted across the River Plate into neighboring Uruguay, where haze hung over the capital of Montevideo and the tourist resort of Punta del Este, Uruguayan navy Capt. Marcelo Larrobla said.