A growing number of countries evacuated citizens from Beirut on Thursday as Israel's bombing of the Lebanese capital intensified and governments worldwide urged their citizens to get out.

Israel has sent its troops into southern Lebanon after two weeks of intense airstrikes, in an escalating conflict that has drawn in Iran and risks drawing in the United States.

Israel's military bombed the heart of Beirut on Thursday, after Israeli forces suffered their worst losses on the Lebanese front in a year of clashes with the Iran-backed group.

Dozens of Greeks and Greek Cypriots boarded a Greek military aircraft at Beirut airport, many of them children clutching soft toys and school bags. In the cramped conditions onboard, some played with glow sticks, while others slept on their parents' laps as the plane left behind the smoking city below.

The plane dropped off 38 Cypriots at Larnaca airport in Cyprus, about 200 km (124 miles) west of Lebanon, and continued on to Athens, where 22 Greek nationals disembarked.

"We were trapped, there was no other way to leave because Middle East aeroplanes are full and the earliest flight you can get is in ten days," Giorgos Seib told Reuters on the runway at an airport outside Athens after landing.

"Every day the situation gets worse and we don’t know what will happen tomorrow."

Expatriates in Lebanon have been scrambling to leave and governments from China to Europe have drawn up plans to get their citizens out.

Russia organised a special flight from Beirut on Thursday for the family members of Russian diplomats. Australia said it has organised hundreds of airline seats for its citizens to leave.

This week, life in Lebanon became too traumatic for many as Israel's military urged residents of more than 20 towns in the south to evacuate their homes immediately. Nearly 2,000 people have been killed over the past year, including 127 children, the country's health minister Firass Abiad said on Thursday.

"It was very hard, very traumatic I've never lived through anything like that before," Clea Rita Barsamian, a 21-year-old hospitality management student who had been studying in Lebanon for two years, said shortly after landing in Larnaca.