Israel says it has expanded its ground operation against Hamas, with residents in Gaza reporting the heaviest shelling since the conflict began 13 days ago.
In a statement, Israel’s military said “additional forces” had joined “the effort to combat terror” in Gaza.
Four Palestinians died, including two children and the son of a senior Hamas official, in new airstrikes on Sunday.
UN Secretary General Ban Ki-moon is due to arrive in Qatar later to meet Palestinian President Mahmoud Abbas.
His visit is part of a regional tour aimed at helping Israelis and Palestinians “end the violence and find a way forward”, the UN said.
But the death toll continued to rise at the weekend, with the number of Palestinians killed now at more than 350 – the vast majority of them civilians.
Five Israeli soldiers and one Israeli civilian have died since Prime Minister Benjamin Netanyahu launched the military offensive on 8 July.
The Israel Defense Forces (IDF) sent ground troops into Gaza on Thursday after 10 days of heavy air and naval barrages failed to stop rocket fire from Gaza.