A boy uses a wheelchair to transport water containers in a displacement camp in the Al Mawasi area in Khan Younis on Friday. AFP

The World Food Programme has warned that a massive public health crisis is looming in Gaza due to the lack of clean water, food and medical supplies.

"We've seen massive displacement over the last weeks and months, and we know that combination and the heat can cause a rise in diseases," said Richard Peeperkorn, WHO's representative for Gaza and the West Bank.

"We have water contamination because of hot water, and we will have much more food spoilage because of the high temperature. We will get insect mosquitoes and flies, dehydration, heat stroke."

Extreme heat has killed hundreds worldwide as the northern hemisphere summer begins. Peeperkorn said in Gaza, due to poor water and sanitation conditions, the number of cases of diarrhoea were 25 times higher than usual.

Contaminated water and poor sanitation are linked to diseases such as cholera, diarrhoea, dysentery and hepatitis A, according to the WHO.

The WHO has been unable to carry out medical evacuations from Gaza since the closure of the Rafah crossing in early May.

Peeperkorn said an estimated 10,000 patients still required medical evacuation from Gaza, half of whom are suffering from ailments related to the war.

Reuters