Ben Carson, the new secretary of the US Department of Housing and Urban Development (HUD), is facing a backlash after referring to slaves brought to the United States against their will as "immigrants".

In an introductory speech to staff at the HUD after he was confirmed by the Senate last week, Mr Carson shared anecdotes from his past career as a neurosurgeon and praised immigrants who worked long hours to build a better life for their children.

"There were other immigrants who came here in the bottom of slave ships, worked even longer, even harder for less," said Mr Carson, who is African-American.