A vast cloud of ash spewing from a Chilean volcano forced dozens of flights to be canceled Tuesday across South America, while mud and rain mixed with ash poured down on the resort areas in the region.

All flights in and out of the two busy Buenos Aires airports were scrapped after meteorologists said a portion of the cloud had moved as far as the Argentina capital, even though at 5,000 meters (16,000 feet) high it was not visible to residents.

More than 90 percent of the flights in an out of Uruguay also were canceled, airport officials said.

In the winter resort of Bariloche, residents were without electricity or drinking water after the eruption of the Puyehue volcano on the Chilean side of the Andes ridge led to a torrent on mud and volcanic ash.

The problems were worsened by heavy rains that mixed with ash and caused power generators to short circuit, creating more havoc.

"I came with my family the day of the eruption. Since then I can't understand what is happening," said Augusto Reales, a tourist from northern Argentina, as he boarded a bus to leave the resort area. "We can't stay with so much uncertainty."

On Lake Nahuel Huapi, one of the main tourist attractions, the emerald green waters were covered with patches of black ash.

"The eruption has begun to lose power but the active phase of the volcano is going to last for weeks or months," said Gustavo Villarosa, a volcanologist.

The price for face masks surged in several days to the equivalent of eight dollars, prompting warnings from local officials.

But the main worry for Bariloche was the closure of its airport -- its runways blanketed with a thick coat of ash -- just ahead of the ski season, the big draw for the local economy.

So far 4,000 people have been evacuated from 22 rural Chilean communities surrounding the Puyehue volcano, which rumbled to life on Saturday after showing no activity since 1960, when it erupted following a magnitude 9.5 earthquake.

Northwesterly winds on Tuesday pushed the giant column of ash over parts of southern Argentina, as Chilean officials visited houses urging residents to leave the remote region below the volcano, which stands at 2,240 meters (7,350 feet) above sea level.

In Sao Paulo, the Brazilian airports authority told AFP that 10 flights bound for Argentina had been canceled due to the ash cloud.

Because of the potential danger to jet engines, numerous carriers and aviation authorities were scrapping flights in the area.

In Santiago, a total of 16 flights were canceled, including all of those headed to Buenos Aires and Montevideo and three for Sao Paulo.

Airports in southern Argentina have been closed since Saturday's eruption of the volcano in neighboring southern Chile.

In Chile, authorities said volcanic activity had diminished but that heavy rains threatened to provoke avalanches that could could affect residents in the region.

The eruption forced Bariloche, population 50,000, to declare a state of emergency Saturday and close its airport.

It also forced a major border crossing to close due to low visibility, and dropped ash on the upscale Argentine resort town of Villa La Angostura.

The rains that began late Monday could prove a disastrous mix with the fine volcanic dust spewing from the volcano, 870 kilometers (540 miles) south of the capital Santiago near the border with Argentina, in Chile's Lago Ranco region.