The tent camps stretch for more than 16 kilometres (10 miles) along Gaza's coast, filling the beach and sprawling into empty lots, fields and town streets. Families dig trenches to use as toilets. Fathers search for food and water, while children scavenge in garbage and wrecked buildings for scraps of wood or cardboard for their mothers to burn for cooking.

Over the past three weeks, Israel's offensive in Rafah has sent nearly a million Palestinians fleeing the southern Gaza city and scattering across a wide area. Most have already been displaced multiple times during Israel's nearly 8-month-old war in Gaza, which is aimed at destroying Hamas but has devastated the territory and caused what the United Nations says is a near-famine.

The situation has been worsened by a dramatic plunge in the amount of food, fuel and other supplies reaching the UN and other aid groups to distribute to the population. Palestinians have largely been on their own to resettle their families and find the basics for survival.

“The situation is tragic. You have 20 people in the tent, with no clean water, no electricity. We have nothing,” said Mohammad Abu Radwan, a schoolteacher in a tent with his wife, six children, and other extended family.

“I can't explain what it feels like living through constant displacement, losing your loved ones,” he said. “All of this destroys us mentally.”

Abu Radwan fled Rafah soon after the Israeli assault on the city began on May 6 as bombardment neared the house where he was sheltering. He and three other families paid USD 1,000 for donkey carts to take them to the outskirts of Khan Younis, about 6 kilometres (3.6 miles) away, where it took a day living outside before they could assemble the materials for a makeshift tent. Next to the tent, they dug a toilet trench, hanging blankets and old clothes around it for privacy.

Families usually have to buy the wood and tarps for their tents, which can run up to USD 500, not counting ropes, nails and the cost of transporting the material, the humanitarian group Mercy Corps said.

Israeli authorities controlling all entry points into Gaza have been letting greater numbers of private commercial trucks into the territory, the UN and aid workers say. More fruits and vegetables are found in markets now, and prices on some have fallen, Palestinians say.

Still, most homeless Palestinians can't afford them. Many in Gaza have not received salaries for months and their savings are depleting. Even those who have money in the bank often can't withdraw it because there is so little physical cash in the territory. Many turn to black market exchanges that charge up to 20 per cent to give cash for transfers from bank accounts.

Meanwhile, humanitarian convoys with supplies for the UN and other aid groups to distribute for free have fallen to nearly their lowest levels in the war, the UN says.

Previously, the UN was receiving several hundred trucks a day. That rate has dropped to an average of 53 trucks a day since May 6, according to the latest figures from the UN humanitarian office OCHA on Friday. Some 600 trucks a day are needed to stave off starvation, according to USAID.

In the past three weeks, most of the incoming aid has entered through two crossings from Israel in northern Gaza and via a US-built floating pier taking deliveries by sea. The two main crossings in the south, Rafah from Egypt and Kerem Shalom from Israel, are either not operating or are largely inaccessible for the UN because of fighting nearby. Israel says it has been letting hundreds of trucks through Kerem Shalom, but the UN has only been able to collect about 170 of them on the Gaza side over the past three weeks because it can't reach the crossing.

Entry of fuel has fallen to about a third of what it was before the Rafah offensive, according to OCHA. That reduced amount has to be stretched between keeping hospitals, bakeries, water pumps and aid trucks working.

The American humanitarian group Anera “is having difficulty distributing what we are able to bring in to the people who need it because there's so little fuel for trucks,” its spokesperson Steve Fake said.

Most of those fleeing Rafah have poured into a humanitarian zone declared by Israel that is centred on Muwasi, a largely barren strip of coastal land. The zone was expanded north and west to reach the edges of Khan Younis and the central town of Deir al-Balah, both of which have also filled with people.

“As we can see, there is nothing humanitarian' about these areas,” said Suze van Meegen, head of operations in Gaza for the Norwegian Refugee Council, which has staff operating in Muwasi.

Much of the humanitarian zone has no charity kitchens or food market, no hospitals operating, only a few field hospitals and even smaller medical tents that can't handle emergencies, only pass out painkillers and antibiotics if they have them, according to testimony from Mercy Corps. “It's just a matter of time before people begin to suffer greatly from food insecurity,” the group said.

The Muwasi area is mostly coastal dunes with no water resources or sewage systems. With human waste deposited near the tents and garbage piling up, many people suffer from gastrointestinal diseases such as hepatitis and diarrhea, as well as skin allergies and lice, Mercy Corps said.

One aid worker who fled Rafah said he was lucky and could afford to rent a house in Deir al-Balah. “You can't walk” in the town from all the tents that have arisen, he said, speaking on condition of anonymity because his agency had not authorised him to speak.

Many people he sees in the street are yellow with jaundice or hepatitis, and “the stench is disgusting” from the sewage and piles of garbage.

Israel says its offensive in Rafah is vital to its war aim of destroying Hamas in Gaza after the group's October 7 attack, in which militants killed some 1,200 people and abducted around 250 others from southern Israel. Israel's campaign in Gaza triggered by the attack has killed some 36,000 people, according to Gaza's Health Ministry.

Aid groups have warned for months that an attack on Rafah will worsen Gaza's humanitarian disaster. So far, Israel's operations have been short of its planned all-out invasion, though fighting has expanded over the past three weeks from the eastern parts of Rafah to central districts of the city. A strike Sunday hit a tent camp in a western part of Rafah, causing a large fire and killing at least 45 people, according to health officials. Prime Minister Benjamin Netanyahu acknowledged a “tragic mistake” had occurred.

From the exodus the assault has caused, satellite photos taken last week show dense new tent camps running the length of the coast from just north of Rafah to outside Deir al-Balah. The ramshackle tents and shelters are densely packed in mazes of corrugated metal and plastic sheets, blankets and bedsheets draped over wooden sticks for privacy.

Tamer Saeed Abu'l Kheir said he goes out at 6 am every day to find water, usually returning around noon to the tent outside Khan Younis where he and nearly two dozen relatives live. His three children, aged 4 to 10, are always sick, but he said he has to send them out to collect wood for the cooking fire, though he worries they'll come across unexploded bombs in the wrecked houses.

His aging father has trouble moving so has to use the bathroom in a bucket, and Abu'l Kheir has to regularly pay to transport him to the nearest hospital for kidney dialysis.

“Wood costs money, water costs money, everything costs money,” said his wife, Leena Abu'l Kheir. She broke down in sobs. “I'm afraid I'll wake up one day and I've lost my children, my mother, my husband, my family.”