'Stop fighting and start talking' UN chief tells Israel and Palestinians

United Nations chief Ban Ki-moon demanded that Israel and Hamas halt the spiralling violence in Gaza as he pushed diplomatic efforts to end bloodshed that has killed 620 Palestinians.

Following top-level truce talks in Cairo, the UN secretary-general headed to Israel to deliver his message in person as the 15-day conflict showed no sign of easing.

"My message to Israelis and Palestinians is the same: stop fighting, start talking and take on the root causes of the conflict so that we are not at the same situation in the next six months or a year," he said.

In Cairo, US Secretary of State John Kerry discussed ceasefire proposals with Egypt's President Abdel Fattah al-Sisi with both voicing guarded hopes of an end to the violence.

But neither side showed any willingness to pull back, with Israel refusing to halt its fire without finishing a ground operation to destroy tunnels used by militants for cross-border attacks.

Even as the diplomats talked, Palestinian rockets continued to fall on central Israel, prompting US airline Delta to indefinitely suspend its flights to the Jewish state over security concerns.

And there was more death on the ground in Gaza where the Palestinian toll rose over 620. Among the dead were two children and nine women, one of whom was pregnant, medics said.