Republican presidential candidate Mitt Romney was booed by an African-American crowd on Wednesday when he told them he would eliminate President Barack Obama's signature policy achievement, the US healthcare overhaul.

Romney's conservative message did not go down very well at the annual convention of the NAACP, a civil rights organization whose African-American members are among Obama's strongest supporters.

The reaction was not uniformly negative. Romney received a standing ovation at the end and there were numerous instances of applause throughout the speech.