A Washington Post report that US President Donald Trump imitated the accent of Indian Prime Minister Narendra Modi in a private conversation about Afghanistan has set Twitter aflutter.

Someone identified as "Professor Qa @MuslimDiasporas," tweeted that it was "racist impressions of Indian accent" and "Sagar Keer @sagark1985" tweeted: "I wonder what the bhakts will think about Trump imitating Modi's accent."

And dozens of tweeters posted the extract from the Washington Post or commented on it.

The Hill, an influential Internet publication specialising in politics, likened the alleged incident to Trump using a word for excrement to refer to African countries and Haiti as claimed by a Democratic Party leader, Senator Dick Durbin.

However, Hillary Clinton, the Democrat who ran against Trump, has publicly dishonoured Mahatma Gandhi with her stereotype of Indian Americans, saying "He (Gandhi) ran a gas station down in St. Louis."

Some gas stations in the US are run by Indian, leading to one of the derogatory steretypes.