Martin Griffiths, the UN's humanitarian chief, has announced the arrival of 14 more trucks carrying humanitarian aid into Gaza.
He said it was "another small glimmer of hope" for Palestinians, but warned they still need "more, much more."
The charity Oxfam welcomed the move, as well as yesterday's first load of aid, but said sending "a few trucks a day is simply not sufficient."
Earlier, Israeli PM Benjamin Netanyahu told troops that his people are in a battle for their lives and said the war against Hamas was "do or die."
The Israeli military has vowed to intensify air strikes on Gaza and warned Palestinians still in the north of the territory to flee south.
Iran's foreign minister warned Israel and the US that the Middle East may spiral out of control if Israel does not immediately stop its military action.
It's been more than two weeks since Hamas launched its assault on Israel, killing more than 1,400 people. Palestinian officials in Gaza say more than 4,600 have been killed since then.
UN agency says 29 staff killed in last two weeks
Meanwhile, the UN's agency for Palestinian refugees, says 29 of its staff have now been killed since the war between Hamas and Israel broke out earlier this month.
The agency - known as UNRWA - described being "in shock and mourning". It had previously reported the deaths of 17 staff members.
"Half of these colleagues were teachers," the agency added of its latest toll.
Thousands of Gazans have sought shelter at UNRWA facilities since Israel launched retaliatory strikes on Hamas after the organisation carried out deadly attacks on Israeli military posts and kibbutzes on 7 October - killing more than 1,400 people and taking more than 200 hostages into Gaza.
The Hamas-run health ministry in Gaza says more than 4,600 have been killed there.
BBC