Iranian delegates joined officials from the five permanent members of the U.N. Security Council and Germany in a second round of nuclear negotiations in Kazakhstan.
The so-called P5+1 talks are presided over by EU foreign policy chief Catherine Ashton. She said in a statement Friday that negotiators were looking for a "balanced" position from Iran regarding what she described as a "very clear and concise proposal for a confidence-building measures."
February talks in Kazakhstan included efforts to get Iran to suspend some of nuclear research in exchange for an easing of economic sanctions. U.N. inspectors this year said they suspected there were military dimensions to certain parts of Iran's nuclear program, an allegation Iran denies.
Deputy Iranian negotiator Ali Bagheri suggested in comments published by Iran's semiofficial Fars News Agency that a tit-for-tat exchange dominated the Friday talks.
"Iran believes that what is referred to as confidence building measure, which includes a set of actions that need to be agreed upon and brought into action by both sides, is part of a comprehensive solution and not an insignificant part of the solution or something alongside it," he said.
A Western diplomat told the BBC on condition of anonymity that P5+1 negotiators were confused by Iran's stance so far.
"There were some interesting but not fully explained general comments on our ideas," he said.