"The inspectors will go early next week to Arak," in central Iran, Olli Heinonen, deputy director general of the International Atomic Energy Agency (IAEA), told journalists.

His comment came after a meeting in Vienna with Iran's deputy national security chief Javad Vaeidi and IAEA ambassador Ali Asghar Soltanieh aimed at finalising a plan "on clarifying the open issues associated with the scope and content of Iran's (uranium) enrichment programme."

"We had good discussions. We made constructive progress," Vaeidi told the press conference, adding that "the next meeting will be at beginning of August in Tehran."

Iran said on July 13 that it would let IAEA inspectors visit the Arak reactor.

Ahead of the talks, which had initially been planned for Wednesday and Thursday, Soltanieh said UN and Iranian experts would seek to put together a working framework of "precise rules" concerning any inspections of Tehran's nuclear facilities.