"If confirmed, these are shocking and shameful comments from the President of the United States. Sorry, but there is no other word one can use but racist'," Rupert Colville, spokesman for the UN human rights office, told reporters in Geneva.
He was referring to comments reportedly made by Trump during a meeting on Thursday with lawmakers about immigration reform, demanding to know why the United States should accept citizens from "shithole" countries.
The comments, first reported by The Washington Post, sparked anger among Democrats and Republicans and revived questions about Trump's tendency to make racially charged remarks.
"You cannot dismiss entire countries and continents as 'shitholes' whose entire populations, who are not white, are therefore not welcome," Colville said.
He also took issue with Trump's reported suggestion that the United States should welcome immigrants from places like Norway, whose population is overwhelmingly white, instead of from African countries and Haiti.
"The positive comment on Norway makes the underlying sentiment very clear," Colville said.
"Like the earlier comments made vilifying Mexicans and Muslims, the policy proposals targeting entire groups on grounds of nationality or religion, and the reluctance to clearly condemn the anti-Semitic and racist actions of the white supremacists in Charlottesville – all of these go against the universal values the world has been striving so hard to establish since World War II and the Holocaust," he said.
"This is not just a story about vulgar language. It's about opening the door wider to humanity's worst side, about validating and encouraging racism and xenophobia that will potentially disrupt and destroy the lives of many people.
"This is perhaps the single most damaging and dangerous consequence of this type of comment by a major political figure," he added.