PARIS -- A senior official of the United Nations nuclear supervisory body said Thursday that talks a day earlier in Iran had ended inconclusively and international inspectors had not been given access to a site that they suspect may have been used for testing bomb triggers.
The official, Herman Nackaerts, deputy director of the International Atomic Energy Agency, said the discussions "could not finalize" a document that "once agreed, should facilitate the resolution of outstanding issues regarding possible military dimensions of Iran's nuclear program."
He declined to say whether any progress had been made.
The talks have been going on for months, veering from apparent optimism last May when Yukiya Amano, the I.A.E.A. director general, said there had been a decision "to conclude and sign" an agreement, to far more muted recent assessments. Before Wednesday's talks, Mr. Amano said, "The outlook is not bright."
Mr. Nackaerts was speaking as he returned from Tehran to Vienna, where agency has its headquarters. He said no date had been set for further talks.
"We will work hard now to try and resolve the remaining differences, but time is needed to reflect on the way forward," he said.
"As on previous occasions, we were not granted access to Parchin," he said, referring to a military site 20 miles south of Tehran that inspectors want to examine for evidence of bomb trigger tests.
While Western powers suspect Iran is seeking nuclear weapons technology, Tehran says its program is for civilian purposes.
Iranian officials are scheduled to meet in Kazakhstan this month with representatives of six powers -- the United States, China, Russia, Britain, France and Germany -- for the next round in a long-running series of talks about curbing Iran's uranium enrichment program. So far those talks have also been inconclusive.
Steven Erlanger contributed reporting.
This article originally appeared in The New York Times.