The United Nations Middle East envoy warned on Tuesday (19 May) that the people of the Gaza Strip are desperate and angry at everyone for their plight and it is up to Israel and Palestinian authorities to prevent an implosion of the enclave.

In his first briefing to the UN Security Council, Nickolay Mladenov described his shock at the devastation in Gaza after last year's 50-day war between Hamas militants and Israel.

He said the people were angry at Israel for its blockade, the closure of the Rafah border crossing with Egypt, Hamas for imposing a "solidarity tax" and the international community for not honouring reconstruction pledges.

"There is a clear moral and humanitarian imperative not just for the United Nations and the international community, but primarily for the Israeli and Palestinian authorities to prevent the implosion of Gaza," Mladenov said.

"Gaza is desperate and angry," he said of the territory, home to 1.8 million Palestinians.

Mladenov said he and Secretary-General Ban Ki-moon would engage with Israeli Prime Minister Benjamin Netanyahu's new government to explore options for a return to peace talks on a two-state solution.

Mladenov urged Israel to freeze settlements and reverse recent decisions to advance such activity. The UN and most countries consider settlements that Israel has built on territory captured in 1967 as illegal.

"There should be no illusions about the impact of these unilateral actions," Mladenov said.

"They not only undermine the collective hopes of those longing for a just resolution of the conflict, but they again call into question the viability of achieving peace based on the vision of two states."

Mladenov also called for Palestinian unity between Gaza, which has been controlled by Islamist movement Hamas since 2007, and the West Bank where the more secular, Western-backed Fatah party runs the Palestinian administration.