Chilean officials ordered most residents already evacuated from homes near an erupting volcano to stay in shelters and with family and friends Sunday due to the threat of deadly landslides. The ash spread across the Pacific, prompting authorities to suspend flights in Australia and New Zealand.

The Cordon Caulle volcano's activity had diminished, but there was still a threat of deadly landslides containing mud and water as well as rocks and ash thrown from the volcano, Chile's National Geology and Mines Service said in a statement.

About 4,000 Chileans have been evacuated since the volcano began erupting June 4. The agency said the area north of the volcano is in danger of landslides and avalanches.

Thousands of passengers in Australia and New Zealand were affected Sunday as the ash cloud approached the two countries. Australia's national carrier, Qantas Airways, grounded flights within the country and in New Zealand.

National carrier Air New Zealand did not cancel or delay any flights but adjusted flight routes and altitudes to ensure aircraft remain clear of any ash, company spokeswoman Tracy Mills said. The drifting clouds of fine grit can severely damage airplane engines.

Volcanic ash hovering over the Argentine capital of Buenos Aires and the nearby Uruguayan capital of Montevideo forced officials there to cancel flights late last week, but air traffic began returning to normal Friday night and was operating normally Sunday.

Several airports in the nearby southern Argentine region of Patagonia remained closed. Sunday's winds began blowing ashes in a northeasterly direction, toward the Patagonian cities of Villa La Angostura and San Martin de los Andes, vulcanologist Hugo Moreno said.

Moreno said that scientists discovered during a flyover of the volcano Saturday that it was not spewing material through a 3-mile-long fissure, but through a crater measuring 980 feet to 1,300 feet in diameter.

Chile has more than 3,000 volcanoes along its Andean spine, and 500 of these are considered geologically active. About 60 Of these have erupted in the past 450 years.

The Cordon Caulle is located 620 miles south of the Chilean capital, Santiago.