The White House said on Sunday that it supports Israel's decision to delay releasing 600 Palestinian prisoners, citing the "barbaric treatment" of Israeli hostages by Hamas.

Hamas will not hold talks with Israel through mediators on any further steps in the fragile, phased ceasefire agreement unless Palestinian prisoners are released as agreed, group official Basem Naim told Reuters on Sunday.

Hamas says talks with Israel about further steps in the Gaza ceasefire deal are conditional on Palestinian prisoners being freed as agreed. Israel said on Sunday it was delaying the release of more than 600 Palestinians in return for six living and four dead hostages who had been freed,