At least 21 martyred in Israeli strike on Christian town in north Lebanon

Jerusalem (Reuters): Israel expanded its targets in its war with Hezbollah militants in Lebanon on Monday, killing at least 21 people in an airstrike in the north, health officials said, while millions of Israelis took shelter from projectiles fired back across the border.

So far the main focus of Israel's military operations in Lebanon has been in the south, the Bekaa Valley in the east and the suburbs of Beirut.

The strike in the Christian-majority town of Aitou hit a house that had been rented to displaced families, the town's mayor Joseph Trad told Reuters. In addition to the deaths, eight people were injured, the Lebanese health ministry said.

Local television aired footage of the aftermath of the attack in Aitou, showing rescue workers searching through piles of rubble and medics lifting a victim, wrapped in white shroud, into an ambulance. Burned vehicles and trees were strewn across the site of the strike, and thick smoke rose into the air.

Israel ordered residents of 25 villages in southern Lebanon to evacuate to areas north of the Awali River, which flows some 60 km (35 miles) north of the Israeli frontier.

Prime Minister Benjamin Netanyahu, visiting the military base in central Israel where four soldiers were killed on Sunday by a Hezbollah drone strike, said Israel would continue to attack the Iran-backed movement "without mercy, everywhere in Lebanon – including Beirut".

At the Masnaa border crossing with Syria, Jalal Ferhat, his wife and five children were among those offloading belongings from buses, hoping to leave Lebanon.

"There are strikes in our neighbourhood and destruction, and they (Israeli forces) hit near my house," said Ferhat, 40, from Baalbek, a Hezbollah stronghold in eastern Lebanon. "I have children, you can't just stay where you are. We tried going to another place...we had to leave again."

In central Israel, residents rushed to shelters as sirens sounded. The military said three projectiles that had crossed from Lebanon had been intercepted. No injuries were reported.

The conflict between Israel and Hezbollah resumed a year ago when the militant group began firing rockets at Israel in support of Palestinian militants Hamas at the start of the Gaza war, and has escalated sharply in recent weeks.

Israeli strikes have killed at least 2,309 people in Lebanon over the last year, the Lebanese government said in its daily update. The majority have been killed since late September when Israel expanded its military campaign. The toll does not distinguish between civilians and combatants.

Israel says its operations in Lebanon are aimed at securing the return of tens of thousands of people displaced from their homes in northern Israel.