GENEVA - Almost 20,000 people have been internally displaced in south Lebanon and elsewhere since early October, a U.N. agency said on Monday, as violence escalates on the Lebanese-Israeli border following the eruption of the Gaza war.

The International Organization for Migration said 19,646 people had been displaced inside Lebanon since it began tracking movements on Oct. 8, the day after an assault on Israel by Hamas militants and an Israeli counteroffensive on Gaza.

It said the movements were mostly by those fleeing the south although some departures were also reported elsewhere.

The Israeli authorities have also been evacuating dozens of towns and communities from the north of Israel.

Lebanon's heavily armed Hezbollah group and Israel have been exchanging fire on an increasingly frequent basis all along the border, the worst escalation since the two sides fought a war in 2006.

Hezbollah says 27 of its fighters have been killed in the clashes since Oct. 7, while Lebanese security sources say 11 fighters from Palestinian groups in Lebanon, which are allied to Hezbollah, have also died.

Israel's military says seven troops have been killed along the frontier area.

(Reporting by Emma Farge; Editing by Edmund Blair)