A deal on Iran's nuclear power could mark the start of a change in the relationship between the country and the rest of the world, US President Barack Obama has said.

President Obama told ABC's George Stephanopoulos that he believed President Hassan Rouhani would like to "seize that opportunity" but that he would "have to deal with his politics at home".

He spoke as foreign ministers from six world powers are having intensive talks in Austria to try to reach a nuclear deal with Iran before Monday's deadline.

The six nations - US, UK, Russia, China, Germany and France - want Iran to curb its nuclear programme in return for the lifting of UN sanctions. Iran says it is not seeking nuclear weapons, but wants atomic energy.

Video courtesy of ABC