A province in Argentina declared an economic emergency on Thursday to aid towns where falling ash from Chile's erupting volcano is endangering livestock and keeping tourists away.

The emergency in Neuquen province follows a similar measure by the national government in other parts of Patagonia where agriculture has been hit by accumulating volcanic ash.

The decree by Gov. Jorge Sapag will mean that those affected can receive tax benefits, among other measures.

Chile's Cordon Caulle volcano began erupting June 4, spewing ash that has disrupted flights in countries ranging from Uruguay to Australia.

The ash has also blanketed towns across the border in Argentina. In the area of Villa La Angostura, located 38 kilometres from the volcano, up to 30 centimetres of ash has accumulated on the ground.

The ash has made it difficult to drive safely on roads, and the eruption came just as resorts in the mountain towns were preparing for ski season.

An ash plume rises above the Puyehue-Cordon Caulle volcano chain near Entrelagos, Chile, on June 5. (Carlos Gutierrez/Reuters)

"Today we can't anticipate the season's final results, but we can say that this has ruined the start of the winter season in the coming days," said Roberto Alonso, mayor of Villa La Angostura.

Residents in the town have been working to clean up the ash, said Alejandro Curiluck, a business owner in Villa La Angostura. "In 15 days we should be operating. The big problem is that the volcano keeps sending up ashes," he said.

Satellite images on Thursday showed the main ash cloud from the erupting volcano stretching about 1,400 kilometres toward the east-southeast, Chile's National Geology and Mines Service said in a statement.

"The eruption process continues and it's possible that an increase in activity could occur again, with episodes similar or greater in intensity than those that have occurred so far," the agency said.

The ashes are causing problems for Argentine farmers whose sheep herds are now roaming in pastures covered with ash.

According to official figures, there are more than two million sheep in Patagonia, of which more than half are affected by the ash.

In response, Argentina's Agriculture Ministry declared an emergency on Wednesday in the provinces of Chubut, Rio Negro y Neuquen.

Regional airports in Patagonia have also been shut down for more than a week due to the cloud of fine grit, which can damage airplane engines.

Buenos Aires's main airports reopened on Wednesday and international flights were operating again.