London, August 4 (RHC)-- Iran’s vow to avenge the assassinations of Hamas leader Ismail Haniyeh and Hezbollah military chief Fuad Shukr heightens fears of regional conflagration.

Several Western governments, including the United States, the United Kingdom and France, have called on their citizens to leave Lebanon immediately as tensions rise in the Middle East following the assassination of Hamas’s political chief Ismail Haniyeh, blamed by Iran on Israel and the United States.

Haniyeh’s killing in Tehran on Wednesday, hours after the Israeli assassination of Hezbollah’s military chief Fuad Shukr in Beirut, has triggered pledges of vengeance from Iran and the so-called “axis of resistance.“

Lebanese group Hezbollah, an ally of the Palestinian group Hamas, and the Israeli army have been trading cross-border fire since the Israeli assault on Gaza began in October after Hamas led a rare attack inside the Israeli territory, killing an estimated 1,139 people and taking roughly 240 others captive.

Iran-backed groups from Lebanon, Yemen, Iraq and Syria have already been drawn into Israel’s nearly 10-month war on Gaza.  But the assassinations this week of Haniyeh and Shukr have heightened fears of a regional conflagration.

On Saturday, Israel’s ally, the U.S., said it would move additional warships and fighter jets to the region and asked its citizens in Lebanon to leave on “any ticket available”.

The U.S. embassy in Beirut asked its nationals to “prepare contingency plans” if they choose to stay in Lebanon and be prepared to “shelter in place for an extended period of time.”  The UK’s Foreign Office also urged its citizens in Lebanon to leave “now while commercial options remain available.”

“Tensions are high, and the situation could deteriorate rapidly,” British Foreign Secretary David Lammy said in a statement.  “While we are working round the clock to strengthen our consular presence in Lebanon, my message to British nationals there is clear – leave now.”

On Sunday, the French Ministry for Europe and Foreign Affairs issued a travel advisory, inviting its citizens in Lebanon to leave “as soon as possible” due to the risk of a military escalation.  “In a highly volatile security context, we once again call the attention of French nationals, particularly those passing through, to the fact that direct commercial flights and ones with stopovers to France are still available,” the ministry said.

Meanwhile, Canada told its nationals to avoid all travel to Israel.  “The security situation can deteriorate further without warning,” the Canadian government said in a travel advisory.

The soaring tensions have also forced major airlines, including Dutch airline KLM, Lufthansa, Emirates, Air France, Turkish Airlines, Singapore Airlines and Swiss Airlines, to ground their flights to Israel, Iran and Lebanon.

“Many Lebanese are immigrants, and some came for their summer vacations,” said Al Jazeera’s Ali Hashem, reporting from Beirut.  “With many airlines cancelling and with the disruption of flights, people will want to leave as soon as possible before the retaliation starts.”  

Al Jazeera's correspondent noted that the Lebanese prime minister had already stated the country had the right to retaliate against any aggression.  “Lebanon is a country currently without a president, a caretaker prime minister.  Just like the disruption in the airport, there is a disruption in the governance in this country.  That’s why you don’t see a lot of government officials talking and reacting.”

Early on Sunday, a barrage of more than 50 rockets were fired from southern Lebanon into northern Israel. Explosions were seen over the Upper Galilee area, as Israel deployed its missile defense system to intercept the rockets.

The rocket attacks came after Israel struck several areas in southern Lebanon overnight, the official Lebanese media reported on Sunday.  “Israeli warplanes carried out an air raid on the outskirts of the Al Mahmudiyah area, followed by a second airstrike east of Kafr Rumman,” the Lebanese National News Agency reported.

Iran on Saturday said it expects Hezbollah to hit deeper inside Israel and no longer be confined to military targets.

Meanwhile, Israel bombed tents housing displaced Palestinians in the yard of Al-Aqsa Martyrs Hospital in Gaza’s Deir el-Balah, killing at least three and wounding 18 others. The attack came hours after a strike on a Gaza City school-turned-shelter killed 17 people.

At least 39,550 Palestinians have been killed and 91,280 others wounded in Israel’s war on the besieged and bombarded enclave.