Israel's renewed offensive in Gaza has reportedly left at least 322 children dead and 609 wounded in the Palestinian territory in the past 10 days, UNICEF said on Monday.

The figures include children who were reportedly killed or wounded when the surgical department of Al Nasser Hospital, in southern Gaza, was hit in an attack on March 23, the UN children's agency said in a statement.

UNICEF said most of these children were displaced, and sheltering in makeshift tents or damaged homes.

Ending a nearly two-month ceasefire in the war with Hamas, Israel resumed intense bombing of Gaza on March 18 and then launched a new ground offensive.

"The ceasefire in Gaza provided a desperately needed lifeline for Gaza's children and hope for a path to recovery," said UNICEF Executive Director Catherine Russell.

"But children have again been plunged into a cycle of deadly violence and deprivation."

Russell added: "All parties must adhere to their obligations under international humanitarian law to protect children."

The UNICEF statement said that after nearly 18 months of war, more than 15,000 children have reportedly been killed, over 34,000 reportedly injured, and nearly one million children have been displaced repeatedly and denied basic services.

UNICEF called for an end to hostilities and for Israel to end its ban on humanitarian aid entering Gaza, which has been in force since March 2.

It also said children who are sick or wounded should be evacuated to receive medical attention.

"Food, safe water, shelter, and medical care have become increasingly scarce. Without these essential supplies, malnutrition, diseases and other preventable conditions will likely surge, leading to an increase in preventable child deaths," UNICEF said.

"The world must not stand by and allow the killing and suffering of children to continue," it added. (AFP)