VIENNA - A US think-tank said Iran may have violated last year's interim nuclear agreement with six world powers by stepping up efforts to develop a machine that could enrich uranium much faster. Iran's development of advanced enrichment centrifuges is sensitive because, if successful, it could enable it to produce potential nuclear bomb material at a rate several times that of the decades-old model now in use. Western officials were not immediately available to comment on the allegation by the Washington-based Institute for Science and International Security (ISIS), which closely tracks Iran's nuclear program. There was no immediate comment from Tehran.
