No deal has been reached yet but significant progress in the talks of the P5+1 nations (China, Russia, the UK, the US, France and Germany) with the Islamic republic ended on a positive note in Swiss city of Geneva, officials said.
"The US and Iran are exploring a nuclear deal that would keep Tehran from amassing enough material to make a bomb for at least a decade, but could then allow it to gradually build up its capabilities again," The Wall Street Journal reported.
Such a deal would represent a significant compromise by the US, which had sought to restrain Tehran's nuclear activities for as long as 20 years.
According to the daily, the US has been pushing for a freeze that would establish a period of time during which Iran would remain at least 12 months away from being able to fuel an atomic bomb-a so-called breakout period.
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Asked if Iran must accept that breakout period through the lifetime of an accord, a US official signaled that may not be necessary, the daily said.
Such a move has been opposed by Republican leadership and expressed concern over such a long time frame.
"If you're going to do all of this and then just end up with a 10-year agreement, you just really haven't accomplished near what people had hoped," said Senator Bob Corker, Chairman of the powerful Senate Foreign Relations Committee.
The White House reiterated that the chances of a deal is 50-50.
"The President and I have, on a number of occasions when asked this question, noted that our odds of reaching an agreement with Iran are 50-50 at best. I think that continues to be a fair assessment of where things stand," the White House Press Secretary, Josh Earnest, said.
Two deadlines for a permanent agreement have been missed since a November 2013 interim deal in which Iran was given limited sanctions relief in exchange for diluting its stock of fissile material from 20 per cent enriched uranium to five per cent.