The fate of the hostages held in the Gaza Strip can only be clarified during a ceasefire, according to a senior member of the Palestinian militant organization Hamas.
Part of the negotiations is to reach an agreement on a ceasefire "in order to have enough time and security to collect definitive and more accurate data on the captured Israelis," said Basem Naim, a member of Hamas' political wing, in a statement posted on Telegram.
The abductees were in various locations in the embattled Gaza Strip and in the hands of various groups, the statement said. Some of them were also lying "under the rubble" together with Palestinians who had been killed.
"We are negotiating to get heavy equipment for this purpose," said the Hamas official.
Naim was responding to questions from media outlets about whether Hamas had rejected the recent US compromise proposal because it could not release 40 hostages in a first phase of a three-phase deal.
According to media reports, the first phase provided for the release of women, female soldiers, men over 50 and men under 50 with serious medical problems.
In the most recent negotiations, however, Hamas declared that it did not have 40 living hostages from these categories. This raised fears that significantly more hostages may be dead than is currently believed.
Israel had previously assumed that just under 100 of the 130 or so hostages remaining in the embattled Gaza Strip were still alive.
According to media reports, the US compromise proposal was presented by CIA Director William Burns at the negotiation talks in the Egyptian capital Cairo on Sunday.
The proposal envisaged Hamas releasing 40 of the hostages held in exchange for 900 Palestinian prisoners - including 100 sentenced to life imprisonment for the murder of Israelis - in the course of a six-week ceasefire.
Israel would in turn allow up to 150,000 displaced Palestinians to return to the north of the Gaza Strip, the proposal said.
Hamas is insisting on a permanent ceasefire and the complete withdrawal of Israeli troops from the contested coastal area. The Israeli government is keeping open the possibility of continuing the fighting after a ceasefire.
As Israel and Hamas are not talking directly to each other, the US, Qatar and Egypt are acting as mediators.