World powers will meet Iranian top representatives to discuss the Islamic state's disputed nuclear programme in Istanbul at the end of January, a Russian official said.
The so-called "P5+1" nations -- Iran and the five permanent UN Security Council members along with Germany -- had not all met since a June meeting in Moscow.
But an unnamed Russian source on Thursday told the state RIA Novosti agency that the next meeting has been provisionally scheduled for the end of the month in Istanbul -- host of the first such talks in April 2012.
The source did not name a specific date or say when one might be announced.
Three prior "P5+1" meetings have been held at the most senior level envisioned for the Istanbul session.
None has produced a compromise that sees the powers accept Iran’s right to enrich uranium in exchange for its provision of access to closed nuclear facilities and promise not to make higher-grade material.
Israel, widely considered the Middle East's sole if undeclared nuclear power, and much of the West suspects Iran is trying to develop atomic weapons under the guise of its nuclear programme, a charge Tehran denies.