Trump to announce recognition of Jerusalem as Israel's capital on Wednesday

US President Donald Trump will formally recognise Jerusalem as the capital of Israel on Wednesday, the White House has said, marking a controversial break with precedent that could provoke a significant backlash.

Trump administration officials have described the risky move as a "recognition of reality" that the city has been used as a base for many Israeli government offices.

US embassies around the world have been warned to step up security measures in preparation for Trump's announcement, which will come at 1pm in Washington.

On the the eve of his contentious decision on Jerusalem's status, the president held calls with US allies in the Middle East to discuss the issue.

The White House said Trump talked with Saudi Arabia's King Salman and Egyptian President Abdel Fattah al-Sisi late on Tuesday, both of whom have warned Trump against moving the US embassy in Israel to Jerusalem.

Sisi urged Trump "not to complicate the situation in the region by taking measures that jeopardise the chances of peace in the Middle East", the Egyptian leader's spokesman Bassem Radi said in a statement.

Sisi also confirmed "Egypt's consistent position on maintaining the legal status of Jerusalem within the framework of international standards and relevant United Nations resolutions," he said.

Saudi Arabia's King Salman warned President Donald Trump that moving the US embassy for Israel to Jerusalem was a "dangerous step" that could rile Muslims worldwide.

"Moving the US embassy is a dangerous step that provokes the feelings of Muslims around the world," state-run Al-Ekhbariya TV quoted King Salman as telling Trump in the phone call.

They are just the latest in a series of leaders Trump has called as he readies to break with decades-long US policy and de facto recognize Jerusalem as Israel's capital.

In an open letter to the American president, Morocco's King Mohammed VI on Tuesday expressed his "deep personal concern" and "the great concern felt by Arab and Muslim states and peoples" over moves to recognise the city as Israel's capital and transfer the US embassy there.

The monarch was writing as head of the 57-member Organisation of Islamic Cooperation's Al-Quds Committee, which lobbies on issues related to the city, holy to three of the world's major religions.

Earlier on Tuesday Trump informed Palestinian president Mahmoud Abbas by phone of his intention to move the embassy from Tel Aviv to Jerusalem.

Abbas "warned of the dangerous consequences such a decision would have to the peace process and to the peace, security and stability of the region and of the world," a PA spokesperson said.

The move has been widely condemned in the Arab world and internationally.

A Jordanian palace statement quoted King Abdullah as telling the US president that such a decision would have "dangerous repercussions on the stability and security in the region" and would obstruct US efforts to resume Arab-Israeli peace talks.

Israel regards Jerusalem as its capital, a position nearly the entire world rejects saying its status should be determined in peace talks with the Palestinians.

East Jerusalem, which includes the Old City, is considered occupied Palestinian territory under international law.