Israeli airstrikes hit around 40 targets across the Gaza Strip over the past day, the military said on Friday, hours after Hamas rejected an Israeli ceasefire offer that it said fell short of its demand to agree a full end to the war.

Gaza has become a "mass grave" for Palestinians and those trying to help them, medical charity MSF said on Wednesday.

Gaza's civil defence agency said Thursday that a rash of Israeli air strikes killed at least 40 people, most of them in encampments for displaced civilians, as Israel pressed its offensive in the Palestinian territory.