President Donald Trump yesterday recognised the disputed city of Jerusalem as Israel's capital -- a historic decision that overturns decades of US policy and risks triggering a fresh spasm of violence in the Middle East, reports AFP. "I have determined that it is time to officially recognize Jerusalem as the capital of Israel," Trump said from the White House.

"It's the right thing to do." The declaration calls into question seven decades of deliberate diplomatic ambiguity about the final status of a holy city vociferously claimed by both Israelis and Palestinians. Trump also kicked off the process of moving the US embassy from Tel Aviv to Jerusalem, making good on a campaign promise dear to evangelical Christian and right wing Jewish voters -- as well as donors.

He said his decision marked the start of a "new approach" to solving the thorny conflict between Israel and the Palestinians.

Trump's predecessors -- from Bill Clinton to George Bush -- made similar promises on the campaign trail, but quickly reneged upon taking office, and the burden of war and peace.

This most unlikely of presidents, who came to office with no foreign policy experience and denouncing experts, was determined to show his arrival in Washington spells the end of business as usual.

"Many presidents have said they want to do something and they didn't do it," Trump said in the hours leading up to his historic address.

"Whether it's courage or they changed their mind, I can't tell you," he said. "I think it's long overdue."

The announcement leaves many angry US allies and leaders across the Middle East trying to find a measured response and hoping that the tinderbox region is not destined for yet another round of bloodletting.

Pope Francis joined a list of leaders warning of an historic misstep that could trigger a surge of violence.

"I cannot silence my deep concern over the situation that has emerged in recent days," the pontiff said Wednesday, one day after speaking by phone with Palestinian president Mahmud Abbas.

The pontiff added that maintaining Jerusalem's status quo was important "in order to avoid adding new elements of tension to an already volatile world that is wracked by so many cruel conflicts."

In a frantic series of calls, the leaders of Saudi Arabia, Egypt, Jordan, the European Union, France, Germany and Turkey also warned Trump against the move.

Moving the US embassy will probably take years to implement, but the repercussions of Trump's decision are likely to be swift.

Hundreds of Palestinians burned US and Israeli flags as well as pictures of Trump in the Gaza Strip, while relatively small clashes erupted near the flashpoint West Bank city of Hebron.

The Palestinian armed Islamist movement Hamas has threatened to launch a new "intifada," or uprising.

Palestinians called for three days of protests -- or "days of rage" -- starting Wednesday.

Anticipating protests, US government officials and their families were ordered to avoid Jerusalem's Old City and the West Bank, though the situation remained largely calm Wednesday.

Turkish President Recep Tayyip Erdogan called for a summit of the Organisation of Islamic Cooperation (OIC), the main pan-Islamic body, in Istanbul on December 13 "to display joint action among Islamic countries" over Jerusalem.