ISTANBUL (AP) - The EU foreign policy chief says the latest nuclear talks between Iran and six world powers have been constructive and that the two sides will meet again in Baghdad on May 23.

Catherine Ashton says future talks will be guided by the "principle of a step-by-step approach and reciprocity." That indicates the international community is ready to reward Iran if it reduces fears that it may use its atomic program to make weapons.

She also said after the talks in Istanbul on Saturday that Iran has a right to a peaceful nuclear program. At the same time, she says the Nuclear Nonproliferation Treaty must be the "key basis" for future talks.