The German mediator working on a prisoner exchange deal between Israel and Hamas was in the Gaza Strip on Tuesday, to hear the Islamist group's response to the latest proposal. Hamas was expected to express reservations to the latest Israeli counter-offer, which would free captured IDF soldier Gilad Schalit in exchange for the release of some 1,000 Palestinian prisoners. Senior Hamas leader Mahmoud Zahar met with the mediator to update him on the results of recent consultations with the group's top leadership in Damascus. Speaking about the deal with Al-Hayat on Tuesday, Moussa Abu Marzouk, deputy chairman of the Hamas political bureau, said that the latest Israeli offer had included a "withdrawal from previous stances" which the group found problematic. "Every time we get close to an agreement, the Israelis back out at the last minute," he complained. "We're sticking to our demands out of national common sense. We're determined to come to a reasonable prisoner swap which will bring about the release of our imprisoned heroes. "We won't give up on these demands, that's our commitment to [the prisoners]," he vowed. Abu Marzouk went on to tell the London-based newspaper that the mediator had planned to arrive in the Strip two days ago, but was delayed by weather in Germany. He opined that despite efforts by the German mediator, "It seems that it's not enough to seal a deal, especially after Israel's withdrawal. "The German mediator isn't the first, and he won't be the last," Abu Marzouk quipped. Earlier this week, Abu Marzouk was quoted by a Web site affiliated with the movement as saying that Schalit will not become another Ron Arad. "Gilad is a captive and we're treating him in a moral way," Abu Marzouk told the Web site on Sunday. "His rights are being respected better that those of our prisoners in Israeli jails." IAF navigator Arad has been missing since 1986 when he ejected over Lebanon.