Israel says it has carried out an air strike against what it said was a "military structure" used by the armed group Hezbollah in southern Lebanon.

The Lebanese health ministry said four people were killed in the strike on a house in the town of Maifadoun, around 30km from the Israeli border.

Security sources told the AFP news agency that the four men were Hezbollah fighters. In an apparent response, the group launched drone strikes on towns in northern Israel, injuring two people.

It comes amid increasing tensions between Israel and Hezbollah, and with Iran which backs the group.

Last week, an Israeli air strike killed senior Hezbollah commander Fuad Shukr in a southern suburb of the Lebanese capital Beirut, in what Israeli officials called an "intelligence-based elimination".

Israeli officials say he was responsible for a rocket attack on the Israeli-occupied Golan Heights last month which killed 12 children and teenagers. Hezbollah has denied any involvement in that attack.

Hours after Shukr was assassinated, the Hamas political leader Ismail Haniyeh was killed in the Iranian capital Tehran - Iran blamed the attack on Israel.
Hezbollah and Iran have vowed to retaliate over the deaths, sparking fears that the tit-for-tat blows could ignite a broader regional conflict.

Several countries, including the US, have urged citizens to leave Lebanon as soon as possible. The country's foreign minister said on Tuesday that he was working to ensure that Hezbollah did not trigger a major escalation with its response to Shukr's death.

The Israeli attack on Maifadoun was carried out by fighter jets, and was guided by intelligence agencies, the Israeli Defense Forces said in a statement posted to social media. Officers from the internal security agency Shin Bet and military intelligence agency Aman provided assistance to the military.

In response, Hezbollah fired what it called a "swarm" of drones at Israel, injuring two people in the northern town of Mazra’a. But a source in the group told the Reuters news agency that the attack was not part of its response to the death of Shukr.

US President Joe Biden met his senior national security team on Monday as concerns of a retaliatory attack on Israel grew.

Mr Biden said he had been briefed on preparations to support Israel should it be attacked, while Secretary of State Antony Blinken said officials were working "around the clock" to prevent an escalation.

The United Nations' rights chief Volker Turk called on "all parties, along with those states with influence, to act urgently to de-escalate what has become a very precarious situation".

Elsewhere, several US military personnel have been injured in a strike on a base in Iraq. The rocket fire on the Ain al-Assed base is the latest in a series of attacks on the facility, which hosts American forces fighting the Islamic State group.