Secretary-General Antonio Guterres on Tuesday emphasized the UN's role as the guardian of international law in the Israeli-Palestinian conflict, days before US President Donald Trump's son-in-law is to present a new Mideast plan to the Security Council.
Jared Kushner, an architect of the Trump administration's blueprint that has enraged the Palestinians, is to brief the council's 14 other members at a behind-closed-doors lunch on Thursday.
"Our position is very clear. We are the guardians of the UN resolutions and international law in relation to the Palestinian question," Guterres told a wide-ranging news conference at the United Nations headquarters.
"We are totally committed to the two-state solution," he added, reiterating his stance that the plan must be based on pre-1967 borders.
The US plan makes numerous concessions to Israel, proposing the establishment of a Palestinian capital in Abu Dis, a suburb of Jerusalem. The Palestinians have long sought the whole of east Jerusalem as their capital.
The US proposal also gives consent for the annexation of Israeli settlements as well as the Jordan Valley, Palestinian territories occupied by Israel since 1967.
The Palestinians, who have strongly criticized Trump's plan, on Tuesday submitted a draft resolution through Tunisia and Indonesia, two non-permanent members of the Security Council.
The draft "strongly regrets" that the Trump plan "breaches international law" and UN resolutions.
It also "undermines the inalienable rights and national aspirations of the Palestinian people, including to self-determination and independence," the draft says.
It is expected to be submitted to a vote in the Security Council on February 11, coinciding with a visit of Palestinian president Mahmoud Abbas
The United States would likely oppose it, using its veto if necessary, should it gain the support of the minimum nine council members required for passage.
Diplomats said the Palestinians could then seek a vote in the United Nations General Assembly, as at the end of 2017 when a majority of UN member states voted to reject Trump's recognition of Jerusalem as Israel's capital.