The UN last night warned of a humanitarian "catastrophe" in Lebanon as Israel launched more deadly air attacks on the seventh day of an assault that has killed at least 245 and displaced half a million people.

Helicopters, ferries and cruise liners began taking foreign nationals to safety but Lebanese civilians remained trapped in a cycle of violence that has left them in fear of each new attack and their infrastructure in tatters.

"The situation is both alarming and catastrophic. There are about 500,000 people displaced already. The situation is extreme," Unicef representative in Beirut, Roberto Laurenti, said.

Lebanon's grim body count continued to mount as Israeli pressed on with its campaign to defeat fighters of the Hizbollah group, killing 31 people in attacks that flattened homes and hit an army barracks.

Prime Minister Fuad Siniora accused Israel of "committing massacres against Lebanese civilians and working to destroy everything that allows Lebanon to stay alive".

US President George W Bush said the current crisis indicates that Syria is trying to "get back into Lebanon".

"There's suspicion that the instability created by the Hizbollah attacks will cause some in Lebanon to invite Syria back in," he said.

US Secretary of State Condoleezza Rice, meanwhile, prepared to visit the Middle East on Friday after talks with UN Secretary-General Kofi Annan.

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