VIENNA — Iran and six world powers seeking to coax Tehran into curbing its nuclear activities appear to be coming to talks later this month without resolving the differences that scuttled previous rounds, according to recent letters exchanged between the two sides.

One letter, shared with The Associated Press Friday, shows Iran seeking an expert-level meeting ahead of the June 18-19 Moscow negotiations to "prepare the necessary ground for the Moscow talks." In response, a senior European Union representative speaking for the six powers suggests there is no need for such preliminary talks because the six remain committed to their "straightforward proposal" presented at the last meeting in Baghdad.

Her letter instead urges Tehran to embrace that proposal, which offers a mix of incentives if Tehran reduces uranium enrichment, which can generate weapons-grade material as well as nuclear fuel. The letters were shared by two diplomats amid a renewed effort in Vienna Friday by the U.N. nuclear agency to coax Iran into reopening a long-stalled probe into suspicions that Tehran worked secretly on atomic arms.

The diplomats demanded anonymity because the correspondence is confidential. The investigation has been stalled for nearly five years by Iran's insistence that it does not need to cooperate because the allegations are based on forged U.S. and Israeli intelligence.

The six powers — the United States, Russia, China, Britain, France and Germany — are watching the Vienna talks closely for signs of Iranian flexibility ahead of their latest attempt to persuade Tehran to stop enriching uranium to a grade that can be turned quickly into the core of nuclear missiles. (AP)