(Adds quotes, context) (Adds quotes) VIENNA, Sept 18 (Reuters) - The European Union said on Thursday it was disappointed with a lack of progress by Iran in addressing concerns about its suspected atomic bomb research, pressuring Tehran to cooperate with a long-stalled U.N. watchdog inquiry. The 28-nation EU made the statement at a board meeting of the International Atomic Energy Agency (IAEA), which for years has been investigating allegations that Iran has worked on designing a nuclear ******. Iran denies the charge. ...