"Two Israeli soldiers killed during combat in north Gaza," the military said in a statement.

The Israeli deaths came as international warnings increased over the spiralling bloodshed and mounting humanitarian crisis in Gaza, on a day in which Israeli troops and Hamas militants engaged in "fierce battles" in the north of the strip.

Warplanes kept up a relentless barrage of strikes on Gaza, where the Hamas-run health ministry said that 8,525 people had died so far, including over 3,500 children.

The ministry later said at least 50 people were killed in an Israeli bombardment of a refugee camp in the northern Gaza Strip.

As the death toll rose, Israel's Prime Minister Benjamin Netanyahu dismissed calls for a ceasefire, saying it would be tantamount to a "surrender" to Hamas, which he has vowed to destroy even as its militants continue to hold at least 240 hostages.

Hamas also released footage of battles within Gaza, including what it said was a military vehicle on fire.

None of this footage could be independently verified, but AFP images showed plumes of smoke rising as Israeli helicopters rained down rockets on the northern Gaza Strip.