VIENNA — In what officials described as a serious, workmanlike and conversational atmosphere, Iran and six world powers have agreed on a timetable and framework for negotiating a comprehensive agreement to end the confrontation over Iran’s nuclear program, the European Union’s foreign policy chief and Iran’s foreign minister said Thursday.

While details were vague and the two delegation leaders declined to take questions at a closing news conference, they said that groups of experts would meet early in March and that the full delegations would meet again on March 17, with the expectation that they would meet monthly.

Catherine Ashton, the European Union’s foreign policy chief, said: “We had three very productive days during which we have identified all the issues we need to address to reach a comprehensive and final agreement. There is a lot to do. It won’t be easy, but we have made a good start.”

Officials refused to describe the topics for the expert meetings, but a senior American official, speaking on the condition of anonymity under the session’s ground rules, said, “Every issue of concern to us is on the table,” including uranium enrichment, Iran’s heavy-water reactor project and its suspected nuclear military research and ballistic missile program. All these issues, the official said, including clarifying the issue of Iran’s past military research, are at least mentioned in a joint plan of action agreed upon with Iran in November in Geneva.