The six nations had asked the Iranians to respond concretely to their demand to curb higher-level enrichment. While Mann said that topic was "addressed," he refused to qualify whether the Iranian response met the expectations of the world powers.
The United States and others suspect that Iran is enriching uranium to develop nuclear weapons. Tehran denies this, saying all of its nuclear goals are peaceful and it is enriching solely to make reactor fuel and medical isotopes. But fears have been fueled by Tehran's refusal to stop enriching or accept uranium from abroad.
While the Islamic Republic has previously mentioned lifting sanctions or staying pending ones, one of the diplomats said Monday's request was the most direct to date.
