Saudi Arabia has called for all citizens to leave Lebanon "immediately" as tensions mount along Lebanon's southern border with Israel.

The Gulf kingdom's embassy in Beirut said it was "closely following the developments" in southern Lebanon, where at least 18 people have been killed in exchanges of fire between Hezbollah and Palestinian militants on one side and Israel on the other.

The dead are mostly fighters but have also included a Reuters journalist and two civilians.

At least three people have been killed on the Israeli side.

Palestinian militant group Hamas launched a massive assault against Israel on October 7.

Israel launched a wave of retaliatory air strikes against the Gaza Strip, killing nearly 3,500 people, mostly civilians.

Hezbollah has since been involved in a series of tit-for-tat incidents with Israel.

After a rocket strike on a Gaza hospital killed hundreds on Tuesday, Hezbollah called for a "day of rage".

Hundreds of Hezbollah supporters gathered in Beirut's southern suburbs on Wednesday to protest the strike.

The Saudi embassy statement said citizens remaining in Lebanon should "exercise caution and stay away from places where gatherings or demonstrations are taking place".

Kuwait this week also warned its citizens against travelling to Lebanon.

The Kuwaiti foreign ministry said citizens wishing to visit "should be patient and postpone travel during this stage" and those already in the country should "return voluntarily if there is no urgent need for their presence".