In a joint statement at the end of three-day talks, officials for both sides said they would meet again in Vienna on March 17, continuing a process likely to take at least six months and probably longer.
Separately, the U.N. nuclear agency confirmed that Tehran is meeting its commitments under the first-step pact that led to this week’s negotiations, which seek a more ambitious deal.
The agency noted that Iran’s stockpile of nuclear material that can be turned quickly into the fissile core of a nuclear warhead had diminished by nearly 20 percent to 161 kilograms (355 pounds) under the first-step agreement, which took effect last month.
Expectations had been modest as the talks started Tuesday. The announcement of an agreement on future talks appeared aimed in part to raise hopes that the negotiations had a chance to succeed.