Updated

A team of U.N. experts has returned from Tehran without agreement on a long-sought deal that would restart its probe of suspicions that Tehran secretly worked on developing nuclear arms.

Iran denies such allegations, asserting that all its nuclear activities are peaceful. It stopped answering questions about the allegations more than four years ago, saying it had provided enough information. New attempts to restart the investigation have dragged on for more than a year, with Tehran insisting on a detailed outline of what U.N. experts of the International Atomic Energy Agency may or may not do in their investigations.

Team head Herman Nackaerts said Friday that "differences remain," and no deal was reached.

He told reporters at Vienna airport that the two sides will meet again in Tehran Feb. 12.