It follows widespread claims that the Israeli military is besieging parts of the north and preventing food aid getting through.

Israel denies its blocking aid and says 50 trucks arrived in northern Gaza today.

The US has threatened to cut military supplies unless more aid is allowed through.

Israel is not allowing international journalists, including the BBC, independent access to Gaza.

Fergal Kean reports now from Jerusalem, a warning his report contains graphic images that may be distressing from the very start.

Not a burden but a duty to the dead and those left after them.

They'd fled here hoping it might be safer.

In Gaza City 13 members of the same family killed by an Israeli airstrike.

I took out my younger brother at the last moment.

He told me I heard mum and dad reciting a prayer.

I don't know how we can go back to our home in the north without my mother or father or brothers.

The Abu A brother mourns his sister.

It's a horrible crime here, says the civil defence officer.

Many dead are being pulled out of homes and from the streets.

Jubalia is cut off by the Israeli army fighting Hamas.

But the horrors being endured here are emerging.

They run to save life and because they fear airstrikes.

Bodies piled into ambulances.

All ages.

Kamel Adwan Hospital in Jubalia is facing a constant stream of casualties.

There is a dire humanitarian crisis.

Israel is accused of refusing or impeding up to 90% of aid to northern Gaza in the last month.

From Jerusalem I spoke to the director.

What is the situation now for you in the hospital?

We are talking about collective punishment for the health system in the Gaza Strip.

Consequently we urge the world to intervene and impose their humanity over the Israeli army.

To open humanitarian corridors that allow the entrance of medical tools, delegations, fuel and food so that we can provide humanitarian services for the children, newborn babies and patients who are in need.

America has warned Israel it may cut arms if it doesn't boost the aid allowed into northern Gaza.

Israel says it's addressing US concerns and its soldiers blame Hamas for the crisis facing civilians, saying medical facilities are used to launch attacks.

In Gaza City they're digging for the dead.

What a child must witness.

They desperately want this to stop.

But no, they cannot make it happen.

Fragol Keen, BBC News, Jerusalem.