The UN Security Council has called for an immediate ceasefire between Israel and Palestinian militants in Gaza.

It comes as US Secretary of State John Kerry heads to Cairo for talks on the crisis amid a mounting death toll.

Over 500 Palestinians, mainly civilians, have been killed since the Israeli offensive began two weeks ago, Gaza's health ministry says.

Twenty Israelis 18 of them soldiers have died, Israel says, as it seeks to end rocket fire on the country.

On Sunday Gaza saw its deadliest day since the start of Israel's Operation Protective Edge, with 13 Israeli soldiers and more than 100 Palestinians killed.

Israel says it has killed at least 120 militants since the ground offensive began on Thursday night.

Sunday's late-night UN Security Council session was convened at the request of Jordan, which is understood to have proposed a strongly worded draft resolution for consideration.

Secretary General Ban Ki-moon spoke out on the situation, describing Israel's operation in Shejaiya as "an atrocious action".

However, the 15-member council instead issued a statement to the press, with Rwanda's UN ambassador calling for "an immediate cessation of hostilities".

Eugene Gasana said members voiced alarm at the escalation of violence during a "sobering session".