An MP with family in Gaza has said people are no longer asking where they can go that is safe, but "where do we want to be when we die?"
Layla Moran, the Liberal Democrats foreign affairs spokeswoman, said the UK government and other international allies are "failing" to prevent civilian casualties by refusing to call for a ceasefire, as she described the desperation felt by Palestinians.
Israel has told people to flee to southern Gaza ahead of an expansion of ground operations in the next phase of the war.
Israel-Hamas war latest: Civil order 'breaking down'
But Ms Moran told the BBC: "There is bombing in the south - there is bombing on the so-called safe route that they were given to get to the south.
"Nowhere in Gaza is safe, and the conversation in Gaza, I'm afraid to say, has changed. No longer are people saying, 'Where do we go to be safe?' - the question they are now asking is 'Where do we want to be when we die?'"
Ms Moran, who became the UK's first MP of Palestinian heritage when she was elected in 2017, said she had three generations of extended family in Gaza - including 11-year-old twins.
She said it was "deeply offensive" for Michelle Donelan, the science secretary, to have suggested that Hamas are giving people orders to stay put.
"That is not what is happening. I find it deeply offensive to suggest that Hamas is giving my family any kind of marching orders. They have nothing to do with Hamas."
Ms Moran said her family, who are sheltering in a church, "can't move" because of Israeli bombing.
"This is not hyperbole, this is not just from [my family] but their friends and family who we are in touch with. I cannot overstress the situation.
"So when I hear from the government that they want to minimise civilian casualties, I have to say to them that they are failing, the strategy of the UK government, America and what they are effectively sanctioning in the way Israel is responding."
The UK government and international allies have been calling for a pause in hostilities to get aid into Gaza and to allow foreign nationals to leave - but they have stopped short of backing a full cessation of the violence.
Ms Moran is calling for a humanitarian ceasefire that gives "political space" to "take the temperature down" following "escalatory language from the Israeli government" and allows for peace talks to begin.
The number of people killed in Gaza since the conflict started has climbed to 8,005, according to the Hamas-led Gaza health ministry. The strip is being bombarded in response to the surprise Hamas attacks on 7 October, in which at least 1,400 people were killed on Israeli soil.
Israeli ground forces, including tank columns, pushed into Gaza over the weekend in what Prime Minister Benjamin Netanyahu described as "only the beginning" of the "second stage of the war".
It has sparked heightened concern about the humanitarian crisis unfolding in the 25-mile strip after bombardments knocked out communications late on Friday night - a blackout that followed an Israeli blockade on water, food, fuel and other essentials reaching 2.3 million Palestinians who are effectively trapped.
Scottish leader's family have 'run out of clean drinking water'
Among those stuck in the besieged territory are the in-laws of Scottish First Minister Humza Yousaf.
He had said on Saturday that he and his wife, Nadia El-Nakla, had not been able to contact her parents since the previous day after communications were knocked out and they did not know if they were dead or alive.
On Sunday, Mr Yousaf said on X that he has now heard from them. He said they are alive but he fears for their safety as "they have run out of clean drinking water".
He said a UN resolution calling for a humanitarian truce must be implemented.
"We need the violence to stop, and for significant amounts of aid to get through without delay," he said.