The UN's new Middle East peace envoy on Thursday urged Palestinian factions to unite and Israel to lift its blockade of the Gaza Strip, on his first visit to the territory.
"I strongly believe that it will hurt the cause of the Palestinian people if division, if the lack of unity, is not addressed as soon as possible," Nickolay Mladenov, who was appointed in February, told reporters in Gaza City.
"I hope that the United Nations will be able to support the efforts to strengthen this unity," he said.
Gaza faces a humanitarian crisis months after a devastating 50-day war between Israel and Hamas, with the international community warning of further conflict without Palestinian reconciliation and a lifting of Israel's blockade.
"We in the United Nations, along with our partners in the international community, have a responsibility to ensure that Gaza is not just being reconstructed... but that the blockade which stops access to construction materials, to movement of people, goods... is lifted," Mladenov said.
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The July-August Gaza war, which killed 2,200 Palestinians and 73 on the Israeli side, has left 100,000 people homeless in the tiny coastal territory, home to 1.8 million people.
Reconstruction of homes has barely begun, with an eight-year Israeli blockade still in place.
Gaza's Islamist de facto rulers Hamas and their West Bank-based rivals Fatah have failed to implement a unity deal they signed in April last year.
The deal was meant to hand over control of Gaza to the Western-supported Palestinian Authority, which Fatah dominates.
With Hamas continuing to control Gaza, Israel has left in place its blockade, which has largely banned the import of building materials, fearing they could be used by militants to make weapons and attack tunnels.