Soon after Hamas official Khaled Meshaal made the remarks on the captives, who include Israelis and non-Israelis kidnapped by Hamas on Oct. 7, the group's armed wing separately said the non-Israelis were "guests" who would be released "when circumstances allow".

Gunmen from Hamas took scores of hostages after rampaging through southern Israeli communities and military bases, killing over 1,300 people. Israel's military says the group is holding 199 hostages in Gaza. Hamas says it has between 200 and 250.

Hamas, which like other factions has long called for the release of the roughly 6,000 Palestinians in Israeli prisons, "has what it needs to empty the prisons of all prisoners," Meshaal, a former Hamas chief who now heads its diaspora office in Doha, told AlAraby TV.

In 2011, Israel swapped hundreds of Palestinian prisoners to win the release of one Israeli soldier, Gilad Shalit, who was held for five years. That kind of exchange - which at the time was criticised by some Israelis as too lopsided - looks an impossible bargain with dozens of people being held.

Israel, which has bombarded Gaza with strikes that have killed hundreds of Palestinians, has said it would act to free the hostages while eliminating Hamas.

The captives are believed to include nationals of countries including Thailand and Germany. Other countries have reported their citizens as missing. Israelis with dual nationality in countries including the U.S. are also believed to have been kidnapped.

In a video message, the spokesman of Hamas' armed wing, Abu Obeida, said Hamas has "a group of detainees of different nationalities, these are our guests and we seek to protect them."

He added: "We will release detainees of different nationalities when circumstances on the ground allow." He did not elaborate.

Another senior Hamas official, Moussa Abu Marzouk, said on Monday that "foreign prisoners cannot be released due to the continued Israeli bombing of the Gaza Strip."