Germany-sponsored talks to free an Israeli soldier for Palestinian prisoners 'became playful,' a Hamas official said Monday, blaming Israel for 'violating all previous agreements.' 'The Israeli side canceled everything that had been agreed upon and wanted to draw up a swap unilaterally and impose it on us,' Mahmoud Zahar, a member of Hamas' politburo, told reporters in Gaza. Thus, the talks 'became playful and can't go on.' Neither Germany, which mediates between Hamas and Israel, nor Hamas 'will accept negotiating for years since it is the (Israeli) cabinet that would have the final decision,' Zahar added. Meanwhile, Zahar denied reports that he had quit from Hamas' crew that negotiates for the prisoner exchange. 'These are untrue Israeli reports,' Zahar said. In December, a Germany envoy exchanged proposals between Hamas, which holds Corporal Gilad Shalit hostage since 2006, and Israel. The two sides could not agree on each other's demands and the efforts have been frozen since then. 