Chile had been organizing both events for months, and until today, the foreign ministry had insisted that they remained on track in spite of the domestic turmoil.
The APEC summit was supposed to have been the backdrop for a critical meeting between US president Donald Trump and Chinese president Xi Jinping. A months-old trade war between Washington and Beijing has hurt exporting countries, including copper-producing Chile.
"This is a blow to Chile's foreign policy," former foreign minister Heraldo Munoz said. "This will have an effect on the economy as well, in terms of hotels, reservations. Chile has always organized events without problems, and now there will be doubts in the short term. This shouldn't last, because Chile has a good image abroad."
APEC, a forum for 21 Pacific rim countries to promote free trade, was supposed to have kicked off in mid-November, while COP25, the United Nations' Climate Change Conference, was scheduled for December. It is not clear where they might now be held instead.
There had been concerns that Chile would be overwhelmed by extensive security and logistical requirements to host the summits in the face of ongoing protests, looting and vandalism that the government of President Sebastian Pinera has not been able to stop, in spite of military deployments and nighttime curfews that have now been lifted.
The protesters are seeking profound economic and social changes to close a wide income gap, and are demanding a constituent assembly to draw up a new constitution.
Opposition parties today presented a constitutional case in the congress against former interior minister Andres Chadwick for alleged human rights abuses. Some are also seeking the ouster of Pinera.
The upheaval has alarmed Chile's business community, which was taken by surprise by the virulence of the protests.