South Africa's ruling ANC decided to downgrade its embassy in Tel Aviv to a liaison office over a U.S. decision to recognize Jerusalem as Israel's capital, ahead of a U.N. vote on Thursday on a resolution urging Washington to drop the move.

The decision was taken at the end of a five-day African National Congress conference, in which Cyril Ramaphosa was elected as its new leader and South Africa's likely next president after 2019 elections, following Jacob Zuma.

"Delegates endorsed the proposal that we must give practical support to the oppressed people of Palestine and resolved on an immediate and unconditional downgrade of the SA (South Africa) Embassy in Israel to a Liaison Office," new ANC Secretary General Ace Magashule said on Thursday.

There was no immediate comment from Israel's Foreign Ministry.

South Africa's ministry for international relations and cooperation said on its website that it was deeply concerned about Trump's move as it would undermine Israeli-Palestinian peacemaking, which has been frozen since 2014.

The South African Board of Jewish Deputies and the South African Zionist Federation jointly condemned the ANC's decision.

The 193-member U.N. General Assembly will hold a rare special session on Thursday at the request of Arab and Muslim states to vote on the draft resolution, which Washington vetoed on Monday in the 15-member U.N. Security Council.

Most countries regard the status of Jerusalem as a matter to be settled in an eventual Israeli-Palestinian peace agreement, although that process has been frozen for over three years.

Israel deems Jerusalem its eternal and indivisible capital and wants all embassies based there. Palestinians want the capital of an independent Palestinian state to be in the city's eastern sector, which Israel captured in the 1967 Middle East War and annexed in a move never recognised internationally.

The ANC's move comes at a time when Israeli Prime Minister Benjamin Netanyahu has been pursuing closer ties with other African countries.

Last month, on a visit to Kenya, Netanyahu announced that Israel was opening a new embassy in nearby Rwanda "as part of the expanding Israeli presence in Africa and the deepening of cooperation between Israel and African countries". Israel is seeking to expel thousands of African migrants to Rwanda.

On Thursday, Netanyahu described the United Nations as a "house of lies" on Thursday and said Israel "totally rejects this vote, even before approval".

Trump upended decades of U.S. policy on Dec. 6 when he recognized Jerusalem as Israel's capital, generating outrage from Palestinians and the Arab and Muslim world, and concern among Washington's Western allies.

When under white-minority rule, South Africa was one of Israel's few allies on the continent. But after the 1994 demise of apartheid, relations cooled as the black-majority ANC took over. The ANC has condemned Israeli occupation of territories where Palestinians seek statehood, while maintaining full diplomatic and trade relations with Israel.