EU foreign policy chief Catherine Ashton will meet Iran's top nuclear negotiator Saeed Jalili in Istanbul on Tuesday as tensions mount over Tehran's disputed atomic programme, her office said.
The meeting "is part of continuing efforts to engage with Iran, led by the High Representative, and in line with the understandings reached at the negotiating round in Moscow in June", a spokeswoman said on Monday.
"While it is not a formal negotiating round, the meeting will be an opportunity to stress once again to Iran the need for an urgent and meaningful confidence building step and to show more flexibility with the proposals ... tabled in Baghdad (in May)."
Ashton talked to Jalili by phone in early August, hoping to get the negotiations back on track.
The so-called P5+1 contact group made up of Britain, China, France, Russia, the United States and Germany have asked Iran to immediately stop enriching uranium because of fears Tehran might be developing nuclear weapons.
Iran rejects the allegations, saying its nuclear programme is peaceful and for energy and development purposes only.
The EU announcement comes amid growing fears that arch-foe Israel might attack Iran's nuclear installations, potentially sparking a major conflict.
Over the weekend, Israeli Prime Minister Benjamin Netanyahu claimed that Iran was "90 percent" towards having a nuclear bomb, insisting that Western powers, led by the United States, should lay down a "red line" Tehran must not cross.
The Israeli premier said Iran was moving rapidly to complete enrichment of the uranium needed to produce a nuclear bomb. "In six months or so, they'll be 90 percent of the way there," he said.
The United States says all options against Iran, including military action, are on the table but rejects any idea of warning lines as political grandstanding which might also put it at a strategic disadvantage.
US ambassador to the United Nations Susan Rice said over the weekend that "there's still considerable time" for Western pressure to work, although it remains the bottom line that "Iran will not have a nuclear weapon".
A diplomatic source in Istanbul said Jalili met Turkish Foreign Minister Ahmet Davutoglu on Monday to discuss the resumption of talks with world powers over Tehran's nuclear ambitions.
"Jalili wanted to come to Turkey to discuss the latest developments on the Iranian nuclear issue," the source told AFP on condition of anonymity.
Earlier this month, EU nations raised the threat of new international sanctions against Iran, with Germany Foreign Minister Guido Westerwelle saying Iran had made no "substantial offer" so far to resolve the dispute.
The last round of EU sanctions, a damaging oil embargo, came into effect on July 1, adding to US financial sanctions aimed at shutting off Iran's oil exports, which account for half of government revenues.
Unlike the tough US measures, EU sanctions are not extra-territorial, affecting solely firms operating in Europe, or assets placed within the 27-nation bloc.