The battle between Israel and Hezbollah, the military group backed by Iran that controls much of the country, has gotten worse, and the prime minister has ordered British nationals living in Lebanon to "leave immediately".

"We are ramping up the contingency plans, I think you'd expect that in light of the escalation," Sir Keir Starmer declared, adding that "we are potentially at a brink" of full-scale conflict.

In anticipation of a potential British national evacuation from Lebanon, the Ministry of Defence (MoD) is deploying 700 troops to neighbouring Cyprus, while the government "continues to advise against all travel to Lebanon".

The situation is said to be worsening "rapidly, with devastating consequences" in the nation, where Israeli strikes are said to have killed over 560 people this week.Sir Keir said: "The most important message from me to British nationals in Lebanon is to leave immediately.

"It is important that we’ve been really, really clear: now is the time to leave.”

The handling of the Afghan evacuation, where 15,000 people were airlifted out of the country, was widely criticised as mismanaged and chaotic.

An estimated 10,000 UK citizens are currently in Lebanon. A senior government source said that the difference, for now at least, was that there were still commercial flights leaving Lebanon.

The 700 troops deployed to Cyprus will join 500 military personnel who were sent there over the summer as part of the MoD's contingency plans for an evacuation operation.

Two British warships are already in the region and Royal Air Force planes and helicopters on standby.

Asked by BBC Radio 4's Today programme if he sensed the world was on the brink of all-out war in the Middle East, Sir Keir said he was “deeply concerned”.

He said he “put it in those terms, that we are potentially at a brink point, and we have to come back from the brink”.

He repeated his call for an immediate ceasefire and de-escalation, along with other ministers.

Defence Secretary John Healey said: “We continue to urge all sides to step back from conflict to prevent further tragic loss of life.

"Our government is ensuring all preparations are in place to support British nationals should the situation deteriorate.

"I want to thank the British personnel who are deploying in the region for their commitment and professionalism.”

Healey held a meeting with fellow ministers, intelligence chiefs and diplomats on Tuesday afternoon to work through the government’s plans.

Officials say the UK already has a significant diplomatic and military presence close to Lebanon, including RAF Akrotiri in Cyprus and two Royal Navy ships - RFA Mounts Bay and HMS Duncan - which have been in the eastern Mediterranean over the summer.

The Royal Air Force also has planes and helicopters on standby.

The escalating conflict in the Middle East is likely to be a significant topic of discussion for the prime minister and other world leaders at the UN General Assembly in New York.

Sir Keir arrived in the city on Tuesday evening local time.

Tensions have been growing across the Middle East since Hamas gunmen attacked Israel on 7 October last year, killing about 1,200 people and taking 251 others as hostages.

The Israel military campaign in Gaza in response to the Hamas attack has killed more than 41,000 people, according to the Hamas-run health ministry.

Previously sporadic fighting between Israel and Hezbollah escalated on 8 October - the day after Hamas's unprecedented attack. Hezbollah fired at Israeli positions, in solidarity with Hamas.

Hezbollah has launched more than 8,000 rockets at northern Israel and the Israeli-occupied Golan Heights. It has also fired anti-tank missiles at armoured vehicles and attacked military targets with explosive drones.Hezbollah's communication devices began blowing up all over Lebanon last week.

The Lebanese government reports that Israel then carried out a major string of airstrikes on Monday that have killed 560 people so far.

About 200 British people were reportedly residing in Gaza before to the start of the conflict, and the British government assisted in organising their evacuation last year.