Hamas's armed wing said Tuesday it would release in the coming days some of the foreign hostages in its captivity, as it vowed to turn Gaza into a graveyard for Israel's military.

"We have informed intermediaries that we will release a certain number of foreigners in the next few days," Abu Obeida, a spokesman for Ezzedine Al-Qassam Brigades, said in a televised address.

Around 240 hostages are believed to be held by Hamas at the moment in Gaza, after the militant group attacked communities across southern Israel on October 7, triggering a fierce bombing campaign and ground incursion of the territory by the Israeli military.

Five hostages have been released to date, including four after negotiations through a diplomatic backchannel and one following an operation by the Israeli army.

The announcement 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.

"Gaza will be a graveyard and a quagmire for the enemy, its soldiers and its political and military leadership," said Obeida.

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 on Tuesday.