The top negotiator with Iran over its nuclear program said she would consult with UN partners in New York after face-to-face talks with Iran's Saeed Jalili, AFP reported.
European Union foreign affairs chief Catherine Ashton aims to meet with world powers in the coming days "in order to assess the situation and to discuss the way forward," her office said after the first direct talks since June on Tuesday night.
The foreign ministers of Britain, China, France, Russia, the United States and Germany are due in New York for the United Nations General Assembly going into a "ministerial week" due to begin formally on September 24.
AFP reported that Ashton plans to meet these key figures in the margins of the UN talks, in a bid to get stop-start international diplomacy over Tehran's contested atomic program back moving.
No statements were made to the press at the beginning of Tuesday's meeting with Iran's top nuclear negotiator Jalili, which was held behind closed doors at the Iranian consulate in the Turkish city of Istanbul.
Described simply as part of ongoing efforts "to seek a diplomatic solution," the talks followed negotiations in Moscow in June, a meeting of the respective heads' deputies in July and phone calls made over the summer, Ashton's statement said.
"While it was not a formal negotiating round it was a useful and constructive meeting and an important opportunity to stress once again to Iran the urgent need to make progress," said the declaration issued by EU High Representative Ashton's spokesman Michael Mann.
World powers have asked Iran to immediately stop enriching uranium because of fears Tehran might be developing nuclear weapons.
Iran rejects the allegations, saying its nuclear program is peaceful, designed for energy and development purposes only.
Jalili met earlier Tuesday with Turkey's Foreign Minister Ahmet Davutoglu to discuss the resumption of international talks over Tehran's atomic program, a diplomatic source told AFP.
Earlier this month it was reported that EU nations are exploring a new raft of sanctions against Iran.
"We might have to decide soon a new round of sanctions in the European Union," German Foreign Minister Guido Westerwelle said.
He added, “I see a growing consensus between my colleagues. We will not accept a nuclear weapon for Iran.”
Last week the UN atomic agency's board approved, with a crushing majority, a resolution criticizing Iran.
The resolution expresses "serious concern that Iran continues to defy" UN Security Council resolutions for it to suspend uranium enrichment, a process which can be used for peaceful purposes but also in a nuclear weapon.
It also highlights the International Atomic Energy Agency's complaint that activities at the Parchin base near Tehran, where it suspects nuclear weapons research took place, would “significantly hamper” inspectors should Iran let them visit.
The resolution stops short of a referral of Iran to the Security Council, but it is significant in that Western nations were able to get Moscow and Beijing on board as they are traditionally more lenient on Tehran, with China a major buyer of Iranian oil and Russia having close commercial ties with Iran.