The two sides are to negotiate a solution to the remaining disagreements and it is expected that they issue a final statement.

Negotiators talked on Thursday morning until 6 a.m. (0400 GMT) in the Swiss city of Lausanne, breaking off for three hours to rest.

Chinese and Russian deputy foreign ministers attended the meeting in absence of the Chinese Foreign Minister Wang Yi and Russian Foreign Minister Sergei Lavrov.

Iranian Foreign Minister Mohammad-Javad Zarif and the US Secretary of State John Kerry held talks over Tehran’s nuclear program last night.

In the meantime, Head of the Atomic Energy Organization of Iran (AEOI) Ali-Akbar Salehi and the US Energy Secretary Ernest Moniz met also on Wednesday night as part of efforts between Iran and the G5+1 aimed at reaching mutual understanding in the negotiations.

This is while the experts and deputies of the G5+1 and Iran were also reported to be present in discussions and consultations.

Reports said that Iran's research and development program on advanced centrifuges have been main topic of Wednesday night discussions, IRNA reports.

Iran and Group 5+1 started their new round of talks in Lausanne, Switzerland, on Thursday to narrow their differences over Tehran's nuclear energy program ahead of a July 1 deadline.

Representatives from Iran and the G5+1 group continue holding successive rounds of talks in Lausanne to narrow the existing differences on Tehran’s nuclear activities.

The two sides have actually missed a March 31 deadline for reaching a mutual understanding on whether they could continue further talks on Iran’s nuclear program.

The potential agreement paves the way for a much broader deal by the end of June which guarantees the peaceful nature of Iran’s nuclear activities in return for a promise by international powers to lift unfair sanctions against the country.