Antonio Guterres speaks to the United Nations General Assembly during the Summit for the Future at U.N. headquarters on Sunday. AP

Speaking to CNN ahead of the annual gathering of world leaders at the UN, Guterres cast doubt on the possibility of a ceasefire in the Gaza Strip between Israel and Hamas after eleven months of war.

"It is for me clear that both sides are not interested in a ceasefire. And that is a tragedy, because this is a war that must stop," Guterres said.

"Neither the government of Israel nor the Hamas really want the ceasefire."

After an intensification of cross-border fire between Israel and Hizbollah this week, Guterres said: "what concerns me (is) the possibility of transforming Lebanon (into) another Gaza."

Hizbollah fighters have traded cross-border fire with Israel for nearly a year in stated support of Hamas, whose Oct.7 attack on Israel triggered the ongoing war in Gaza.

But the exchanges have escalated in recent weeks, as Israel turns its attention to its northern border after significantly weakening Hamas.

Israel on Friday struck the southern suburbs of the Lebanese capital, killing at least 16 Hizbollah members, including a senior commander. Lebanon's health ministry put the death toll at 45 including civilians.

Raising fears of all-out war, Israel and Hizbollah traded heavy fire over the weekend.

Hizbollah deputy chief Naim Qassem said on Sunday his group was in a "new phase" in its battle against Israel, vowing an open confrontation.

Agence France-Presse