The gathering was planned in latest Iran P1+5 meeting in Moscow last month.

“We defend all our nuclear rights and simultaneously respect Non- Proliferation Treaty (NPT) articles as we have already announced Iran is against producing nuclear weapons,” Iranian Foreign Minister Spokesman Ramin Mehmanparast said in a press conference.

The Iranian experts in the meeting are consisted of Foreign Minister, nuclear program and National Security Council experts who discuss the nuclear issue with the experts of the world’s six powers.

The Tuesday meeting was not disclosed in the media as the other meeting in Baghdad and Moscow.

A European Union statement said talks in Istanbul lasted a full day and ended early Wednesday.

The statement said the experts explored positions on a number of technical subjects. The talks will be followed by a meeting between Iran's second nuclear negotiator Ali Bagheri and Helga Schmid, the EU official in charge of the talks.

No date for the meeting was announced.