The European Union says Iranian and international technical experts have exchanged details on proposals to end the standoff over Tehran's nuclear program.
A statement said talks in İstanbul lasted a full day and ended early Wednesday.
The technical talks followed three rounds of negotiations between Iran and six world powers that have failed to produce a breakthrough
The statement said the experts explored positions on a number of technical subjects. The talks will be followed by a meeting between Iran's No. 2 nuclear negotiator Ali Bagheri and Helga Schmid, the EU official in charge of the talks.
No date for the meeting was announced.