“It's not a done deal. There's a realistic chance, but there's a lot of work to be done," Westerwelle said upon his arrival in Geneva on Saturday.

Hopes are now rising that an agreement is just around the corner as US Secretary of State John Kerry and other foreign ministers of the world powers gather in Geneva to join the talks which are aimed at resolving the West’s decade-old standoff with Iran over its nuclear energy program.

On Saturday, Russian Foreign Minister Sergei Lavrov said he sees a "real opportunity" for the negotiations to reach an agreement.

The present round of talks was scheduled to end on Friday, but was extended into Saturday.

On Friday, the Iranian Foreign Minister Mohammad Javad Zarif said there has been a 90-percent progress in the course of the nuclear negotiations between Iran and the sextet of world powers.

Meanwhile, informed sources say the six world powers have accepted the Islamic Republic’s right to enrich uranium. The issue has been Iran’s key red line and a major bone of contention between the two sides.