Hamas fighters seized around 240 Israelis and foreign hostages, according to Israeli authorities. Around 110 have since been freed, mainly during a recent week-long truce.
Israel's military said on Friday it had resumed fighting in the besieged Palestinian territory, blaming Hamas.
The resumption of combat has frustrated hopes for the swift release of the more than 130 captives the Israeli army has said are still being held in Gaza.
The UK has said at least 12 British nationals were killed in the October 7 attacks — in which Israeli officials say about 1,200 people died, mostly civilians — and that a further five are still missing.
But it has not confirmed how many are being held by Hamas.
Israel responded to the October 7 attack by vowing to eliminate the militant group and its subsequent relentless air and ground campaign has killed more than 15,000 people, also mostly civilians, according to the Hamas authorities who run Gaza.
In a statement, Hamas denounced the planned flights and «the participation by the British military in the genocidal war against the Palestinian people».
«We call on Britain to reconsider» its decision, it said.
London did not reveal when its military surveillance flights over the territory would start but stressed they would be unarmed and focused only on hostage recovery efforts.
«In support of the ongoing hostage rescue activity, the UK Ministry of Defence will conduct surveillance flights over the Eastern Mediterranean, including operating in air space over Israel and Gaza,» it said in a statement.
«Surveillance aircraft will be unarmed, do not have a combat role, and will be tasked solely to locate hostages,» the ministry added.
«Only information relating to hostage rescue will