HAMILTON, Canada

UN Secretary-General Antonio Guterres remains concerned about the military escalation in the Middle East, particularly the "multiplication of new fronts," his spokesperson said Tuesday.

"Concerning the situation in the Middle East, I can tell you, and you will not be surprised, that the secretary general continues to follow the situation in that region with great concern," Stephane Dujarric said during a news conference.

"We're also witnessing an increasing number of civilian casualties and a severe humanitarian impact on the well-being of people throughout the region," he said.

Pointing to attacks on energy infrastructure, Dujarric stressed that "the continued attacks on energy infrastructure in the Gulf can have a dramatic impact on the global economy, which is still very dependent on fossil fuels."

He noted that "humanitarian operations across the region are being severely affected by insecurity, supply chain disruptions and airspace closures. The movement of humanitarian personnel remains restricted,” he said, emphasizing that "international humanitarian law is non-negotiable."

Dujarric urged the protection of civilians as well as aid workers, while pledging that the UN would remain in the region to respond to the needs of civilians.

Asked about the alleged strike on a school in southern Iran that reportedly killed more than 160 girls in US-Israel attacks, Dujarric said, "I don't think we can use words that are strong enough to condemn when children die."

"When children die in a school, there will need to be accountability for civilians killed in this conflict and in other conflicts," he said.

Tension has escalated across the region when the US and Israel launched a large-scale attack Saturday against Iran, killing nearly 800 people, including Supreme Leader Ayatollah Ali Khamenei.

Tehran has retaliated with drone and missile strikes targeting Israel as well as Gulf countries, which are home to US assets.