Hamas is seeking guarantees that a new U.S.-backed ceasefire proposal for Gaza would lead to the war's end, a source close to the militant group said on Thursday, as medics said Israeli strikes across the territory had killed scores more people.

The rise of Izz al-Din al-Haddad in the chain of command suggests the group will hold firm to its position demanding a total end to the war before releasing all remaining hostages.

Israel is intensifying military operations in one of the last Hamas strongholds in Gaza, as the sides stake out positions before ceasefire negotiations proposed by US President Donald Trump.