Sir Keir Starmer has repeated calls for British citizens to leave Lebanon “immediately” as the conflict between Israel and Hezbollah continues.

The Prime Minister, who is visiting New York for a meeting of the United Nations General Assembly, once again urged both sides to cease hostilities.

On Wednesday the terrorist group Hezbollah fired a ballistic missile at the Israeli city of Tel Aviv, as Israel carried out strikes in Lebanon.

It's very important that they hear my message, which is to leave and to leave immediately

Israel’s military has said it will activate its reserve brigades.

Sir Keir told broadcasters in New York: “I am very worried about the escalation.

“I’m calling for all parties to step back from the brink, to de-escalate. We need a ceasefire so this can be sorted out diplomatically.

“But I have a very important message for British nationals in Lebanon, which is the time to leave is now.

“The contingency plans are being ramped up, but don’t wait for those. There are still commercial flights.

“It’s very important that they hear my message, which is to leave and to leave immediately.”

Troops have already been sent to Cyprus as the British Government is drawing up plans to evacuate British citizens from Lebanon amid the fighting.

The surface-to-surface missile fired from Lebanon on Wednesday set off air raid sirens in Tel Aviv and across central Israel.

There have been no reports of casualties or damage, according to the Associated Press.

The Israeli army said it struck the site in southern Lebanon from which the projectile was launched.

Hezbollah said it fired a Qader 1 ballistic missile targeting the headquarters of Israel’s Mossad intelligence agency, which it blames for a recent string of targeted killings of its top commanders and for an attack last week in which bombs hidden in pagers and walkie-talkies killed dozens of people and wounded thousands, including many Hezbollah members.

The Israeli military said it was the first time a projectile fired from Lebanon had reached central Israel.