At least 24 people have been killed in an attack on a tent encampment near the city of Rafah in the south of the Gaza Strip, the Gaza Health Ministry said on Friday.
The Hamas-controlled authority said that 47 other Palestinians were injured, blaming Israeli forces for the attack.
The attack hit al-Mawasi near Rafah. Many people had fled there after the Israeli military began its offensive in Rafah at the beginning of May.
Eyewitnesses reported that Israeli tank shells had hit the area.
The Israeli military said that its initial investigations indicated that the attack in al-Mawasi was not carried out by Israeli troops.
Like other developments from inside Gaza, the information could not be independently verified.
Earlier on Friday, about 20 Palestinians were killed during ongoing Israeli army operations against Hamas militants in the Gaza Strip, according to reports from Palestinian medical sources.
The Israeli military said that its operations would continue in the centre and south of the sealed-off coastal area, where humanitarian conditions are said to be critical by UN agencies and international NGOs.
UN Secretary General António Guterres voiced concern on Friday that "lawlessness" in the embattled Gaza Strip was preventing the distribution of humanitarian aid in the region.
Guterres said that inside Gaza, "lawlessness is total,” making it extremely challenging to distribute aid within the area.
He noted that looting of relief supplies and trucks was complicating the distribution process.
"There must be a mechanism guarantee that there is a minimum of law and order that allows for the distribution to take place," Guterres demanded.
He renewed his call for an immediate ceasefire between Israel and Hamas.
The Gaza war was triggered by the massacre of more than 1,200 people by Hamas and allied groups in Israel on October 7 last year.
According to the Hamas-controlled health authority in Gaza, at least 37,431 people have been killed and 85,653 injured in Gaza since the start of the war. The figures do not distinguish between civilians and combatants and cannot be independently verified.