Bolivia's leader said Washington continues to conspire against him - despite US President Barack Obama's pledge of a new era of mutual respect toward Latin America.
Morales says at a 34-nation summit that he asked Obama to publicly repudiate a plot to assassinate him that Bolivian authorities say they crushed this week, killing three alleged mercenaries.
Morales does not allege US involvement in the assassination plot. But he tells reporters that in the 100 days since Obama took office he sees no change in US hostility.
Morales expelled the US ambassador and drug agents last year, accusing them of conspiring with the opposition to incite violence.
Morales was among South American presidents who met with Obama on Saturday.