A tweet posted by former President Barack Obama after the white-supremacist rallies in Charlottesville, Virginia, has quickly become the most liked tweet of all time.

The message against racism following demonstrations by US hate groups that left three people dead has notched over 3 million likes within three days.

"No one is born hating another person because of the color of his skin or his background or his religion..." Obama wrote alongside a picture of him with young children of different races.

President Donald Trump has been criticised for his reluctance to call out white supremacy since the violence.

Trump in a press conference Tuesday doubled down on his assertion that counterprotesters deserved some of the blame for violence in the US town. The comments were lambasted by his Republican Party as well as by Democrats.

House Speaker Paul Ryan tweeted: "We must be clear. White supremacy is repulsive. This bigotry is counter to all this country stands for. There can be no moral ambiguity."

Sen. John McCain of Arizona tweeted: "There's no moral equivalency between racists & Americans standing up to defy hate& bigotry. The President of the United States should say so."