Jimmy Carter has said that Donald Trump's Middle East peace plan would violate international law and urged the United Nations to stop Israel from annexing Palestinian land.

Trump presented his long-awaited plan on Tuesday alongside Benjamin Netanyahu, Israel's Prime Minister and a close White House ally, who shortly afterward signalled he would seek to annex a large part of the West Bank.

Trump's plan recognises Israeli sovereignty over most of its West Bank settlements and the Jordan Valley, as well as an undivided Jerusalem, but Carter, the former US president, said the scheme puts peace at risk.

"The new US plan undercuts prospects for a just peace between Israelis and Palestinians," said Carter, who brokered the landmark 1978 Camp David Accords that brought peace between Israel and Egypt.

"If implemented, the plan will doom the only viable solution to this long-running conflict, the two-state solution."