Obama: Ahmadinejad 9/11 remarks 'hateful'

US President Barack Obama has described remarks at the UN by President of Iran as "offensive" and "hateful".

In a speech on Thursday, Mahmoud Ahmadinejad claimed most people believed the US government was behind the 9/11 attacks.

His remarks triggered a walkout at the UN assembly.

Relations between Iran and the US have been strained over Tehran's controversial nuclear activities.