US President Donald Trump's speech on Sunday will likely be met with skepticism and frustration in the Muslim world, according to experts in the Middle East who said his sudden shift in tone on Islam was unconvincing.

Trump gave his speech in Saudi Arabia, where he ditched his hard-line rhetoric from the 2016 election campaign and instead called Islam "one of the world's great faiths."

Trump delivered the speech during an Arab-Islamic-American summit in Riyadh to leaders of 55 Muslim-majority countries, including Malaysian Prime Minister Najib Abdul Razak.