UN chief says 195 UNRWA staff members have been killed in the war, the highest death toll for staff in UN history.

Secretary-General Antonio Guterres on Friday pleaded for donors to fund the embattled UN agency for Palestinian refugees, warning there was no alternative despite Israeli criticism of the body.

At a pledging conference, Guterres warned that suffering Palestinians would lose a "critical lifeline" without the agency known as UNRWA.

"Let me be clear -- there is no alternative to UNRWA," he said.

"Just when we thought it couldn't get any worse in Gaza -- somehow, appallingly, civilians are being pushed into ever deeper circles of hell."

Philippe Lazzarini, the chief of UNRWA, said the agency will be unable to function beyond August without receiving more funding.

A UN emergency appeal for $1.2 billion for the Palestinians by the end of the year, along with an appeal for neighboring countries, has received less than 20 percent of the funding it needs, Lazzarini said.

UN Secretary-General Antonio Guterres speaks to the media. File photo

Israel, long critical of UNRWA, alleged in January that a number of the agency's employees participated in the October 7 attack by Hamas.

Israel has since ramped up pressure on UNRWA, which fired the employees and promised to investigate.

According to Guterres, 195 UNRWA staff members have been killed in the war, the highest death toll for staff in UN history.

The US Congress has barred further funding for UNRWA. President Joe Biden's administration has instead directed funding for Palestinian civilians to other bodies, while saying that UNRWA is uniquely equipped to distribute aid.

The war started with Hamas's October 7 attack on southern Israel which resulted in the deaths of 1,195 people, mostly civilians, according to an AFP tally based on Israeli figures.

Israel responded with a military offensive that has killed at least 38,345 people in Gaza, also mostly civilians, according to the health ministry in Hamas-ruled Gaza.