United Nations (UN) agencies have expressed concern over the escalating conflict between Israel and Hezbollah.

"We are extremely alarmed by the sharp escalation of hostilities between Israel and Hezbollah and call on all parties to immediately cease the violence and to ensure the protection of civilians," UN High Commissioner for Human Rights Volker Turk's spokesperson Ravina Shamdasani said in Geneva on Tuesday.

Speaking during a press briefing, Shamdasani said that incidents resulting in the deaths or serious injuries of civilians, including children and medical workers, could potentially violate international law and must be subject to independent, thorough, and transparent investigations into the circumstances of the attacks.

The UN High Commissioner called on all states and actors with influence in the region and beyond to take action to prevent further escalation and ensure that international law is fully respected.

The death toll from intensive Israeli air strikes on southern and eastern Lebanon since Monday has reached 558, including 50 children and 94 women, with the injured reaching 1,835, Lebanese Health Minister Firas Abiad said on Tuesday.

Several spokespersons and officials from UN agencies and international organizations also expressed concern over the escalating conflict during the press briefing.

Abdinasir Abubakar, an official from the World Health Organization in Lebanon, reported that some hospitals in the country were "overwhelmed" by wounded people arriving.

He also noted that four healthcare workers were killed on Monday and that there is documented evidence of attacks on medical facilities and even ambulances.

Matthew Saltmarsh, spokesperson for the UN Refugee Agency, expressed grave concern over the escalating conflict, noting that tens of thousands of people were displaced in a short time, with the numbers continuing to rise. He added that the agency is actively seeking new shelters to accommodate those forced to flee their homes.

Deputy Representative of the UN Children's Fund in Lebanon Ettie Higgins warned via video link from Beirut that any further escalation of the conflict would have catastrophic consequences for all children in Lebanon.

"Yesterday was Lebanon's worst day in 18 years. This violence has to stop immediately, or the consequences will be unconscionable," Higgins said.