"The end of the ceasefire in Gaza due to heavy Israeli attacks is cause for great concern," Baerbock said in Berlin, adding that she was planning a trip to Lebanon on Wednesday.

"The images of burning tents in refugee camps are shocking. Fleeing children and internally displaced persons must never be used as leverage in negotiations."

Baerbock stressed that "international law includes the principle of proportionality even in self-defence".

"With the resumption of fighting, the fate of the remaining hostages but also the future of the people in Israel, Gaza and the entire Middle East now again hangs on an extremely thin silk thread," she said.

Germany's top diplomat said she was appealing "in particular to the USA to use its regional influence ... now, because the security of the wider Middle East is affected by this".