The United Nations said on Tuesday it has received permission to send "around 100" trucks of aid into war-shattered Gaza Strip, as humanitarian assistance trickled back in to the territory.

"We have requested and received approval for more trucks to enter today, many more than were approved yesterday," said Jens Laerke, spokesman for UN Office for Coordination for Humanitarian Affairs in Geneva, adding that "we expect, of course, with that approval, many of them, hopefully all of them, to cross today to a point where they can be picked up and get further into the Gaza Strip for distribution."

The good news came as Gaza's civil defence agency said Israeli strikes killed at least 44 people across the war-ravaged Palestinian territory, where Israel has intensified a military offensive aimed at crushing Hamas.

The Israeli army stepped up its offensive in Gaza on Saturday, saying it was aimed at defeating Hamas, the Islamist group that runs the Palestinian territory.

Israeli strikes have since killed scores of people in the besieged coastal territory, according to rescuers.

"Civil defence teams have transferred [to hospitals] at least 44 dead, mostly children and women, as well as dozens of wounded" across Gaza since 1am [8am Hong Kong time], agency spokesman Mahmud Bassal said.

He said eight were killed in a strike on a school sheltering displaced people in Gaza City and 12 in a strike on a house in Deir el-Balah in central Gaza.

Another 15 were killed in a strike on a gas station near the Nuseirat refugee camp and nine in a strike on a house in the Jabalia refugee camp. (AFP)