"I sincerely hope that through this P5+1 negotiation there will be very meaningful progress," he told a press conference in Madrid on Thursday after meeting with Spanish Prime Minister Mariano Rajoy.
He added that he has been discussing Iran’s nuclear issue with Iranian authorities and emphasized that Tehran should prove that its "nuclear development program is genuinely for peaceful purposes.”
The UN chief also told IRNA that he has held talks with the European Union foreign policy chief, Catherine Ashton, adding that she has an “optimistic and logical” view about the negotiations.
Addressing a joint press conference with Turkish Foreign Minister Ahmet Davutoglu in Ankara on Wednesday, Ashton expressed “cautious optimism” about the outcome of the talks between Iran and the P5+1 group.
Ban urged Iran and the P5+1 group - Russia, China, France, Britain, the US and Germany - to show flexibility and emphasized that issues pertaining to the Iranian nuclear energy program should be settled through completely peaceful ways at the earliest.
The six major world powers will meet Iranian negotiators in Almaty, Kazakhstan, for the second round of talks this year on April 5 and 6, with the main focus being on Iran’s nuclear energy program.
Earlier on Thursday, Secretary of Iran’s Supreme National Security Council (SNSC) Saeed Jalili reaffirmed the inalienable right of Iran, as a signatory to the Non-Proliferation Treaty (NPT), to enrich uranium and called on the P5+1 group to recognize Tehran's right to peaceful nuclear energy.
Tehran and the P5+1 have already held several rounds of talks the last round of which took place in Almaty on February 26-27.
The US, Israel and some of their allies claim that Iran is pursuing non-civilian objectives in its nuclear energy program, with the US and the European Union using the false claim as a pretext to impose illegal sanctions against Iran.
Tehran rejects the allegation over its nuclear energy activities, maintaining that as a committed signatory to the NPT and a member of the International Atomic Energy Agency, it has the right to use nuclear technology for peaceful purposes.