Stiff winds blew ash from a Chilean volcano Tuesday in a widening arc across Argentina to the capital, grounding most air travel to and from the country for much of the day.
Since airborne ash can severely damage jet engines, Aerolineas Argentinas and Austral, the country's state-owned international and domestic airlines, canceled all flights within Argentina as well as to and from other countries. At least six international carriers also suspended flights between Buenos Aires and cities in the United States, Europe and South America, and flights from Chile over Argentine territory also were suspended.
Later Tuesday afternoon, Aerolineas announced it was slowly resuming flights from Buenos Aires to the north and east, areas beyond the reach of the thickest part of the plume. But airports closer to the volcano were ordered closed through at least Sunday. LAN Air Lines also was resuming flights over Argentine territory.
The cancellations left the usually bustling international and domestic airports in Buenos Aires nearly deserted as aviation regulators met to study the weather patterns. Geologists have said the Cordon Caulle volcano could keep erupting for several weeks.
The ash cloud was blowing well to the south and away from Chile's capital, Santiago, but at least four international carriers there also suspended flights across Argentina to Buenos Aires, Brazil, Uruguay and Europe as a precaution.
The closest major city to the volcano is San Carlos de Bariloche, just over the border in Argentina, where thick abrasive soot was coating slopes in a string of resorts that depend on the winter ski season, opening in less than two weeks. The plume then stretched northeast before curving east, dumping ash over Argentina's vast ranchlands before reaching the capital and even Paraguay, north of Argentina.
"Given that even this morning the volcano continues to be active, the reopening of the airports isn't expected until the conditions necessary for security can be guaranteed," Argentina's transportation department announced.
Transportation officials were meeting with representatives of Argentina's meteorological service, civil aviation board and airport regulator to figure out where the ash cloud will move next and what to do about it, the statement said.
The ash couldn't be seen in the streets of downtown Buenos Aires by midday Tuesday.
But Jorge Echarran, who runs the emergency council of the surrounding Buenos Aires province, said in a local radio interview that "the cloud is already in the suburbs and is reaching the capital," hovering at an altitude of between 16,400 feet (5,000 meters) and 22,970 feet (7,000 meters).
Closer to the volcano, strong rains that began Monday night increased the danger of rivers getting clogged with ash and then overflowing in flash floods. Evacuations were expanding, with more than 4,000 people already fleeing their homes.
Vulcanologist Jorge Munoz of Chile's National Geology and Mines Service said the eruption so far is considered to be moderate, but that could change. He said the volcano will likely begin to expel lava in the coming days, along with pyroclastic material that can turn waterways into avalanches of mud and rock.
Many people have refused to evacuate despite living below the eruption, which opened a three-mile long fissure along a high-altitude ridge between two volcanic peaks.
That could prove to be fatal, according to Michael Dobbs, a volcano expert at the University of Santiago who said the "eruptive column," more than 6 miles (10 kilometers) high, could collapse, suddenly releasing molten lava, toxic gases and other material measuring 1,300 degrees Fahrenheit (700 degrees Celsius) on communities below.
Associated Press writer Federico Quilodran in Santiago, Chile, and Almudena Calatrava in Buenos Aires contributed to this report.