Authorities in both countries issued a red alert, the highest possible, warning the 9,700-foot Copahue volcano in Chile could erupt at any moment, the BBC reported Tuesday.
The volcano has been spewing gas while thousands of small earthquakes have been recorded, officials said.
"This red alert has been issued after monitoring the activity of the volcano and seeing that it has increased seismic activity," Chilean Interior Minister Andres Chadwick said in a news conference.
"There is a risk that it can start erupting."
Around 460 families living within 15 miles of the volcano would be evacuated, Chile's Emergency Office announced.
In Argentina, around 600 people were ordered to evacuated from the town of Caviahue, less than 10 miles from the volcano.
Copahue, one of the most active volcanoes in the Andes, erupted last December spewing ash and gas almost a mile into the atmosphere.