Previous US leaders have generally chosen Canada or Mexico for their first presidential voyage

US President Donald Trump will urge unity between the world's major faiths on an ambitious first foreign trip that will take him to Saudi Arabia, the Vatican and Jerusalem, the White House said Tuesday.

National Security Advisor HR McMaster laid out a detailed itinerary for the "historic trip," due to start late this week, and confirmed that Trump would address a gathering of Muslim leaders on his "hopes for a peaceful vision of Islam."

Previous US leaders have generally chosen a US neighbour such as Canada or Mexico for their first presidential voyage, but Trump intends to plunge right into some of the world's most difficult spiritual and political conflicts.

In Saudi Arabia, after a day of talks with King Salman and his crown prince, Trump will attend a gathering of dozens of leaders from across the Muslim world.

"The speech is intended to unite the broader Muslim world against common enemies of all civilization and to demonstrate America's commitment to our Muslim partners," McMaster said, adding that Trump will help open a center to de-radicalize extremists.

Trump campaigned for office vowing to destroy "radical Islamic terrorism" and impose "a total ban on all Muslim immigration" to the United States, raising concerns that his election would only deepen distrust between America and the Muslim world.

In office since January 20, he has already attempted to impose a ban on travellers from a group of mainly-Muslim countries, before his order fell foul of the US courts.

But McMaster stressed that Trump would be visiting sites associated with the world's great religions to stress "that we all have to be united and we have to be joined together with an agenda of tolerance and moderation."

Western Wall

After Saudi Arabia, Trump's voyage will take him to Jerusalem, where he will meet Prime Minister Benjamin Netanyahu and visit the Vad Yashem memorial to the Holocaust. The next day he will pray at the Western Wall, one of Judaism's holiest sites.

On the same day, he will meet President Mahmud Abbas of the Palestinian territories in Bethlehem on the West Bank "where he will convey his administration's eagerness to facilitate an agreement that ends" the Israel-Palestinian conflict.

Palestinian officials have put their hopes in Trump to revive the moribund peace process, but -- after early enthusiasm for the Republican billionaire's rise gave way to concerns -- Israeli officials have been on edge in the run-up to the visit.

McMaster failed to answer a direct question as to whether the US government considers the Western Wall to be within Israeli territory, and he said Israeli leaders would not accompany him on his visit to the site in Jerusalem's Old City.

"He's going to the Western Wall mainly in connection with the theme to connect with three of the world's great religions," McMaster said.

After Jerusalem, Trump will head to the Vatican for an audience with Pope Francis. The US leader will celebrate the contributions of Catholics to America and the world, discuss diplomatic issues with the pontiff and tour St Peter's Basilica.

After the Vatican, the trip takes a secular turn with a visit to Belgium to meet European Union officials and attend the NATO summit on May 24-25. He then heads to Italy and the island of Sicily for the G7 summit on May 26 and 27.