The billionaire president is facing youth protests calling for radical education reforms that led to rioting last week and at least 874 arrests.
Officials said student rioting left 90 police officers injured but didn't mention any casualties among the demonstrators. Protesters lit bonfires and set up roadblocks after law enforcement officers denied permission to march. The clashes between the protesters and police took place as the youths tried to stage a march.
More protests Sunday saw at least 30,000 people to the streets of Santiago.
The political troubles preoccupied political leaders as snowstorms paralyzed southern Chile's Magallanes region, which has seen frequent unrest in recent months, first over natural gas prices and poor economic conditions in the south and then environmentalists' opposition to controversial new dam projects.
Officials declared emergency in four regions which appeared cut off by snow and lacking in basic relief supplies for isolated sheep farmers and other communities.
After nine feet of snow authorities reported at least 6,500 residents could have lost contact and could need emergency aid.
Affected residents said 27,000 sheep and 4,000 cattle could also be at risk from lack of food and shelter but had no immediate reports on the status of the families affected by the snowstorms.
"The government has resolved to help those affected, especially those living in Lonquimay," Pinera said, citing the region reported to be worst affected by a polar front that spread chaos in the community of about 10,000 inhabitants.
The area designated as a disaster zone includes Lonquimay, Curralehue, Melipeuco, Curacautin, Pucon, Cunco, Vilcun and Villarrica.
Pinera described the current polar front as the worst the region has seen in 30 years.
Lonquimay Mayor Guillermo Vasquez told reporters temperatures plunged to minus 9.4 degrees Fahrenheit in some of the rural areas.
The sub-zero temperatures froze water and fuel pipes and grounded vehicles, leaving most of Lonquimay without water and many areas without heating.
Overland relief supplies were also hampered by the heavy snow. La Segunda newspaper said only four of 400 boxes of relief supplies sent to the town had reached their destination.
"In four days we have had four months worth of snowfall," said Regional Gov. Miguel Mellado in an interview with Canal 13. "We've got a very difficult situation here."
With 70 percent of the population resident in rural areas, Mellado estimated 6,500 people could be isolated as a result of the snowstorms.
Agriculture Minister Jose Antonio Galilea said he was monitoring the regional situation and taking measures to reach communities with emergency aid.
Local communities can rest assured that personnel, equipment and supplies will reach all those suffering from the severity of the climate and snow storms, he said.
"We have the necessary logistical support and communications."
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