Israel urged world powers on Wednesday to reject what it said was an Iranian offer to partly cut back its nuclear programme in return for an easing of Western sanctions. "Israel in the last few hours has learned that a proposal will be brought before the P5+1 in Geneva in which Iran will cease all enrichment at 20 percent and slow down work on the heavy water reactor in Arak, and will receive in return the easing of sanctions," an official told AFP on condition of anonymity. "Israel thinks this is a bad deal and will oppose it strongly," the official said. The so-called P5+1 group of major powers will meet Iran's nuclear team in Geneva on Thursday and Friday for the latest round of negotiations revived after the June election of Iranian President Hassan Rouhani, a reputed moderate.