A man walks in a smoke-covered park in Buenos Aires on Saturday. - AP

BUENOS AIRES (AP):

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 res-ponsible for this," Fernandez said after riding in a helicopter Saturday over cattle ranches and farms north of Buenos Aires, where hundreds of firefighters worked with the army to ex-tinguish the fast-moving flames.

Clear scrub Bush

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 pile-ups on rural routes made hazy with smoke. The fires are raging just 45 miles (75 kilometres) north of the city and radiate out into the country's Entre Rios and Santa Fe provinces.

Unprecedented crisis

Foul-smelling smoke has shroud-ed 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 neighbours 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 pile-ups. Smog also disrupted air traffic as controllers rerouted planes away from the city's two main airports.