The White House has declined to comment about the image

Google has apologised over a racially offensive image of Michelle Obama that appears when users search for images of the US first lady.

A doctored picture appears at the top of the list under a Google Image search for Mrs Obama.

Google placed a text ad above the image titled "Offensive Search Results", which states: "Sometimes our search results can be offensive. We agree."

But it refused to take the image down from its search results.

The White House has declined to comment about the picture.