Hamas claims it is unable to identify and locate the required 40 Israeli hostages for the first phase of the ceasefire agreement, according to an Israeli official and a source familiar with the discussions, raising fears that perhaps more hostages are dead than is publicly known.

The framework set by negotiators states that during an initial six-week pause in fighting, Hamas would have to release 40 of the remaining hostages, including all womenas well as sick and elderly men. In exchange, hundreds of Palestinian prisoners would be released from Israeli prisons.

Hamas has told international mediators – including Qatar and Egypt – that it does not have 40 hostages alive that meet those release criteria, both sources said. CNN’s file on hostage conditions also shows they exist less than 40 living hostages who meet the proposed criteria.

Hamas’s inability—or unwillingness—to tell Israel which hostages will be released, alive, is a major obstacle, the second source added. With Hamas seemingly unable to reach 40 on the proposed charges, Israel pressed Hamas to fill in the gaps in the original release with younger male hostages, including soldiers, the Israeli official said.

During the months of negotiations since the latest ceasefire, Israel has repeatedly asked for a list of the hostages and their conditions. Hamas has claimed that he needs a break in the fighting so he can locate and gather the hostagesthe same argument he used in November before a week-long pause that ended after Hamas failed to hand over more hostages.

The majority of the nearly 100 hostages those who remain alive are believed to be male IDF soldiers or male reservists. Hamas is expected to attempt to use them in later phases to try to negotiate more significant concessions, including more high-level prisoners and a permanent end to the war.