ALMATY (Reuters) - Major powers will offer Iran some sanctions relief during talks in Almaty, Kazakhstan, this week if Tehran agrees to curb its nuclear program, a U.S. official said on Monday. But the Islamic Republic could face more economic pain if it fails to address international concerns about its atomic activities, the official said ahead of the February 26-27 meeting in the central Asian state, speaking on condition of anonymity. "There will be continued sanctions enforcement ... ...