If the war between Israel and terrorist-designated Hamas spreads to Lebanon, it could be "potentially apocalyptic", warns the UN's head of humanitarian affairs Martin Griffiths.
The situation at the Israeli-Lebanese border is tense with almost daily shelling from both sides.
The leader of the Lebanese Islamist movement Hezbollah, Hassan Nasrallah, held a speech last week in which he warned that if Lebanon is drawn into the war, they will "fight it without restrictions".
And if Lebanon is drawn into the war, Syria and other countries will also be drawn in, according to Martin Griffiths:
The war in Gaza has shown us a new level of brutality. But we are all worried that this is only the beginning.
We are worried about further tragedies and fatalities, he says, describing the risk of the war spreading as "alarming".
According to Griffiths, southern Lebanon is currently a "powder keg", and the UN's humanitarian agency Ocha and other aid organisations are prepared for an expansion of the war.
