Lebanon's president accused Israel on Monday of using phosphorous bombs in its 13-day offensive and urged the United Nations to demand an immediate ceasefire.
"According to the Geneva Convention, when they use phosphorous bombs and laser bombs, is that allowed against civilians and children?" President Emile Lahoud asked on France's RFI radio.
An Israeli military spokeswoman said arms used in Lebanon did not contravene international norms.
"Everything the Israel Defence Forces are using is legitimate," the spokeswoman said.
Lahoud gave no details but said the United Nations had to take concrete action to force Israel to stop its assault.
"The massacre must be stopped as soon as possible. Afterwards we can talk about everything," he said. "A decision has to be taken so that there is an immediate ceasefire."
Lahoud's comments came as US Secretary of State Condoleezza Rice flew to Beirut to seek a "sustainable" ceasefire in Lebanon.
The conflict, triggered when Hizbullah captured two Israeli soldiers, has killed at least 373 in Lebanon as well as 37 Israelis and displaced half a million people in Lebanon.