LAUSANNE, March 16 -- U.S. Secretary of State John Kerry ended a five-hour discussion with Iranian Foreign Minister Mohammad Javad Zarif on Monday morning over Iran's long-disputed nuclear program in Lausanne of Switzerland.

The talks was joined by the head of the Atomic Energy Organization of Iran, Ali Akbar Salehi, and U.S. Energy Secretary Ernest Moniz, who already met earlier on Sunday to discuss the technical issues.

Right after his first meeting with Kerry, Zarif flied to Brussels for talks with EU diplomats and his counterparts from Germany, France and Britain Monday afternoon. He will then return back to Lausanne for further talks with Kerry.

A source close to Zarif said that the top Iranian diplomat seemed to be more confident on reaching a deal.

"Finally, finally we'll get there!" Zarif was cited as saying when leaving for Brussels, adding that "we need to negotiate with all parties by Friday to see what will be the result in the end."

"In some issues we are closer to solution. So we can say that solutions are available, but we're still distant on some issues," he said.