UN Secretary-General Antonio Guterres on Saturday sharply criticized the "unprecedented escalation" of bombardments on Gaza and urged an "immediate" ceasefire.
"Instead of the pause" he had expected, there has been "an unprecedented escalation of the bombardments and their devastating impacts, undermining the referred humanitarian objectives," Guterres said on a visit to Doha.
Guterres spoke as Israel announced Saturday that the war with Hamas had "entered a new phase," with its forces relentlessly pounding Gaza three weeks into a conflict sparked by the deadliest attack in the country's history.
Israel unleashed its bombing campaign after Hamas gunmen stormed across the Gaza border on October 7, killing 1,400 people, mostly civilians, and seizing more than 220 hostages, according to Israeli officials.
The Hamas-controlled health ministry in Gaza said Israeli strikes had killed 7,703 people, mainly civilians, with more than 3,500 of them children.
"This situation must be reversed. I reiterate my strong appeal for an immediate humanitarian ceasefire, together with the unconditional release of hostages and a delivery of humanitarian relief," Guterres said.
"A humanitarian catastrophe is unfolding in front of our eyes."
Qatar, which hosts a political bureau for Hamas in Doha and has provided millions of dollars in financial aid to Gaza, has been linked to mediation efforts for a prisoner exchange between the Palestinian militant group and Israel.
In Doha on Saturday, Guterres met with Qatar's foreign minister Mohammed bin Abdulrahman Al-Thani.
The top diplomat "underscored the State of Qatar's complete rejection of the indiscriminate bombing of the Gaza Strip and the attempts to forcibly displace its people," according to a foreign ministry statement.
He also warned of "the danger of a ground escalation... to the safety of civilians and hostages in Gaza."