* IAEA seeks further Iran clarification on detonators - sources * Issue part of probe into suspected atomic bomb research * Iran says nuclear programme is peaceful; How Iran responds to the U.N. agency's questions about so-called Exploding Bridge Wire (EBW) detonators is seen as an important test of its willingness to cooperate fully with a long-stalled probe into suspected atomic bomb research. Iran says allegations of such activity are baseless, but has offered to help clear up the issues with the International Atomic Energy agency (IAEA), a Vienna-based U.N. body. The United States says Iran's readiness to tackle the IAEA's concerns will be central to the success of efforts to reach a broader diplomatic accord to end the decade-old nuclear dispute, which Tehran and major global powers aim to sign by late July.