The U.N. atomic agency, the IAEA, said Wednesday that a 10th round of talks with Iran over Tehran's alleged efforts to develop nuclear weapons had failed.
“We could not finalize the structured approach document that has been under negotiation for a year and a half,” IAEA chief inspector Herman Nackaerts told reporters.
He added that the IAEA's “commitment to continued dialogue” was “unwavering” but acknowledged that “our best efforts have not been successful so far.”
“We will continue to try and complete this process ... And a date for the next meeting is still to be set,” the inspector added.
The IAEA was pressing Iranian officials to grant access to sites, documents and scientists involved in Tehran's alleged efforts to develop atomic weapons.
The agency says that there is “overall, credible” evidence that until 2003, and possibly since, Iranian scientists conducted research into developing the nuclear bomb.
Iran says the IAEA's findings are based on faulty intelligence from foreign spy agencies such as the CIA and Israel's Mossad -- intelligence it complains it has not even been allowed to see.
Nine rounds of talks since the publication of a major IAEA report in November 2011 have produced no breakthrough.
Separate but linked talks Wednesday evening in Istanbul will see EU foreign policy head Catherine Ashton meet Iran's chief nuclear negotiator Saeed Jalili for the first time since fruitless six-party negotiations in Kazakhstan in April.
IAEA says talks with Iran failed