Washington (AFP) - The United States on Thursday accused Russia of using online trolling to inflame tensions in Chile, where more than 20 people have died in civil unrest.

The White House alluded to a foreign hand in a statement on President Donald Trump's call to his counterpart Sebastian Pinera, who on Wednesday canceled a major summit of Pacific Rim powers as well as a climate change conference over the upheaval.

"President Trump denounced foreign efforts to undermine Chilean institutions, democracy or society," the White House said.

A senior State Department official, speaking on condition of anonymity, pointed the finger at Russia, accusing it of seizing on debate in Chile "and skewing it through the use and abuse of social media -- trolling."

"They have sought to exacerbate divisions, foment conflict and all around act as a spoiler to responsible democratic debate," the official told reporters on condition of anonymity.

The official said that Russia has been stepping up its influence in South America with "very little of it positive."

"They seem to prefer a region divided and they seem to prefer democratic debate mired in conflict, which is unfortunate," he said.

Russia has been at particular loggerheads with the United States over Venezuela, which is wracked by an economic crisis.

Moscow is a major backer of President Nicolas Maduro, whom Western powers consider illegitimate.

US intelligence also accused Russia of deploying social media trolls in hopes of swinging the 2016 US election to Trump, who has spoken with admiration of President Vladimir Putin.

Pinera, like Trump a right-wing billionaire, has taken measures such as reshuffling his cabinet in hopes of placating protesters, who are angry over low salaries and pensions, the state of public health care and a yawning gap between rich and poor in one of Latin America's wealthiest countries.

The United States has had close relations for decades with Chile, with the CIA in 1973 supporting a coup by General Augusto Pinochet that ousted leftist president Salvador Allende.