A senior US official told AFP the talks on the nuclear deal between Iran and the world powers could go into Wednesday.
The source said leaders would choose to extend the talks to create a framework of an agreement "if we are continuing to make progress." The official spoke to AFP on condition of anonymity.
The six world leaders are facing pressure as they face a self-imposed deadline to create an outline for a nuclear agreement. The deal would be to limit Iran's sensitive nuclear activity in exchange for lifting sanctions on the country.
The final deadline for the nuclear deal is June 30.
