Argentine President Cristina Fernandez surveyed more than 200 raging brush fires by air, vowing to prosecute anyone who lit the blazes that have sent smoke billowing across the capital, clouding highways and grounding jetliners.

"People must be held responsible for this," Fernandez said after riding in a helicopter on Saturday over cattle ranches and farms north of Buenos Aires, where hundreds of firefighters worked with the army to extinguish the fast-moving flames.

Interior Minister Florencio Randazzo and Environmental Minister Romina Picolotti urged Argentina's judiciary to investigate owners of charred farmland, to see if fires were intentionally set by some farmers to clear scrub brush on the cheap.

Two people have been arrested in an arson investigation, and more than 15 search warrants have been issued to inspect private farm property, Randazzo said.

Farmers, who burned a tractor and dumped soy and grains on highways to protest export taxes levied on their crops in mid-March, insisted that the recent fires were unrelated to their 21-day strike, which was temporarily suspended April 2.

Farm leaders said that some government supporters were blaming them for the blazes to punish them for their strike.

No one is known to have died in the flames, but at least seven motorists were killed in pileups on rural routes made hazy with smoke. The fires are raging just 75 km north of the city and radiate out into the country's Entre Rios and Santa Fe provinces.

Foul-smelling smoke has shrouded the capital's iconic Obelisk and obscured skyscrapers in a crisis unprecedented in Buenos Aires - a city whose name means "Good Airs" in Spanish. Even its pink presidential palace was dimmed by sooty clouds, and neighbors flocked to doctors with respiratory and eye irritation.

Police declared a "highway emergency" on Friday and Saturday, closing key roadways from the capital and enforcing slow-driving zones to prevent multi-car pileups. Smog also disrupted air traffic as controllers rerouted planes away from the city's two main airports.

Satellite images showed a giant swath of smoke stretching more than 160 km from Buenos Aires to the Atlantic outlet of the River Plate estuary and across to neighboring Uruguay.

The smoke started to appear over the Argentine capital more than a week ago, but visibility deteriorated considerably in the city on Friday and Saturday, with an acrid smell pervading homes and causing watery eyes and sore throats among residents.

Visibility downtown was barely 500 m, and residents' tempers began to fray.

Emergency services directed traffic in some areas of the city on Saturday, while the capital's Jorge Newbery domestic airport diverted incoming aircraft to the international airport outside Buenos Aires - where the smoke also caused some flight departure delays.

Schools canceled sports classes, and a rugby tournament was suspended.

Health officials sought to reassure the public the smoke was not toxic, saying the burned material was organic. But the municipality of Buenos Aires issued a "yellow alert" as a precaution.

(China Daily April 21, 2008)