US intelligence officials fear most of Hamas’s remaining captives in Gaza are already dead, according to a report in the Wall Street Journal.

Israel estimates about 34 captives have died, but the Journal reported that some US officials believe that number should be more than twice as high, which could complicate efforts to reach a new ceasefire deal.

The intelligence sources, who were not identified, said some of the captives may have been killed in Israel’s ongoing assault on the enclave.