UN Secretary General Ban Ki-moon has strongly appealed to Israel and the Palestinians to avoid further escalation of tensions amid concerns that Israeli forces dropped leaflets in the northern Gaza Strip warning residents to evacuate the area.

A statement issued by Ban's spokesman said the UN chief has "learned with concern that leaflets are reportedly being dropped by the Israeli Defence Forces in the northern Gaza Strip this evening," warning tens of thousands of residents to leave their homes and evacuate to Gaza city.

"If true, this would have a further devastating humanitarian impact on the beleaguered civilians of those areas of the Gaza Strip, who have already undergone immense suffering in recent days. The United Nations agencies present in Gaza do not have the resources on the ground to cope with, or provide assistance to, an enormous extra influx of desperate people," the statement said.