Iran's semi-official Fars News Agency quoted an "informed source" on Saturday as denying a report that Iran's chief nuclear negotiator Saaed Jalili had accepted a request for a meeting with a US envoy.
Another Iranian news agency, ISNA, earlier said a US envoy at the Istanbul talks between Iran and six world powers had requested a meeting with Jalili and that he had accepted.
But Fars said its source denied the report and described it as part of a "news wave against the Iranian delegation." Diplomats at the talks in Istanbul also cast doubt on the ISNA report.
The ISNA news agency did not name the US diplomat, but the US delegation at the talks between Iran and the six powers is headed by Under Secretary for Political Affairs Wendy Sherman.
ISNA quoted an unnamed Iranian diplomat as saying: "The American envoy had requested to meet with Saeed Jalili ... and Iran's chief nuclear negotiator has accepted this." There was no immediate US comment on the ISNA report.
Nuclear negotiators for Iran and six world powers were making encouraging progress in bridging differences that have doomed previous meetings meant to reduce fears over Tehran's atomic program, diplomats close to the talks said.
Iran's Saeed Jalili and the EU's Catherine Ashton (Photo: Reuters)
With the meeting just breaking for lunch, the diplomats cautioned against premature optimism about the outcome. But they said the unfolding dialogue between the two sides suggested they would find enough common ground for a second round in several weeks' time.
One of the diplomats, who demanded anonymity because he was sharing information from a closed session, said the Iranians appeared to be moving toward that goal, engaging in discussion about the peaceful use of nuclear energy and the Nuclear Nonproliferation Treaty.
He said the Iranian team had mentioned supreme leader Ayatollah Ali Khamenei's "fatwa," or prohibition, of nuclear weapons for Iran, in the course of the plenary discussions. After lunch the meeting would go into bilateral sessions, he said - a setup that will be closely watched to see if the Americans meet directly with the Iranians.
Such encounters are rare and would indicate a further thaw in tensions at the talks.
"I would say there was a very constructive atmosphere compared to last time ... generally a positive vibe," he said. "The principle seems to be there for future negotiations."
Another diplomat described the just-completed session as a "useful morning's work," saying the Iranians appeared to be looking for a "serious process" at the talks. He too demanded anonymity because his information was privileged.
AP and Reuters contributed to this report