By Steve HollandWASHINGTON (Reuters) - U.S. officials are making intense efforts to gain the release of hostages being held by Hamas militants in Gaza but there is no guarantee of success or a timeframe, a senior Biden administration official said on Friday. Many of the hostages are still being held in Gaza, where the Israeli military has launched air strikes and a ground assault and imposed a siege. The official said it would require a "very significant pause in the conflict" to get the hostages out. The official said the administration was also negotiating with Hamas over allowing foreign nationals trapped in the tiny enclave safe passage out of Gaza. That was deemed unacceptable by U.S. and Israeli officials and rejected, the official said.

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Persons: Steve Holland WASHINGTON, Steve Holland, Costa Pitas, Trevor Hunnicutt, Sandra Maler, Rosalba O'Brien Organizations: Hamas, Biden, U.S Locations: Gaza, Palestinian, Israel