"It is complicated, it is difficult. I think we will stay overnight," Fabius told reporters in Lausanne.
Meanwhile, German Foreign Minister Frank-Walter Steinmeier told RIA Novosti on Tuesday that Iran nuclear talks in Switzerland were proceeding 'excellently.'
"Everything is going well, excellently," Steinmeier said during a short dinner break in the negotiations.
A source in the Russian delegation told journalists that the delegation of P5+1 group and Iran left for dinner and the talks will resume at 9 p.m. local time (19:00 GMT.)
The most recent round of negotiations began in Lausanne on March 19 and was expected to conclude last Sunday. However, the talks were prolonged until Tuesday, as the sides are trying to settle a political framework that will pave the way for a comprehensive agreement on Iran's nuclear program by July 1, 2015.
