US President Donald Trump is to urge the Islamic world to confront extremism in a highly anticipated speech Sunday to dozens of Muslim leaders in Saudi Arabia.

According to excerpts released by the White House, Trump will say the time has come for "honestly confronting the crisis of Islamist extremism", calling on religious leaders to condemn extremist attacks.

But Trump, who has been accused of anti-Islamic rhetoric in the past, will also extend a hand by insisting that "this is not a battle between different faiths".

"This is a battle between barbaric criminals who seek to obliterate human life, and decent people of all religions who seek to protect it. This is a battle between good and evil," Trump is expected to say.

The speech comes on the second day of a visit to Saudi Arabia, part of Trump's first foreign tour that will take him next to Israel and the Palestinian territories and then to Europe.

The first day saw the announcement of hundreds of billions of dollars in trade deals, welcome news for Trump as he faces mounting troubles at home linked with the probe into alleged Russian meddling during last year's election campaign.

Among the agreements was an arms deal worth almost $110 billion with Saudi Arabia, described as the largest in US history, which US Secretary of State Rex Tillerson said was aimed in particular at countering "malign Iranian influence".

Trump to 'be very blunt'

The White House has sought to draw a clear distinction during the visit with Trump's predecessor Barack Obama, who Saudi Arabia and its Sunni Arab allies saw as lecturing and soft on their Shiite rival Iran.

Unlike the Obama administration which would often raise concerns over civil liberties with longstanding Arab allies, Trump has made no mention of human rights during his visit so far.

"We are not here to lecture -- we are not here to tell other people how to live... or how to worship. Instead, we are here to offer partnership -- based on shared interests and values," Trump will say.

A White House official had said Trump would be "very blunt in talking about the need to confront extremism", pointing to "the fact that many in the Muslim world have not only not done enough, they've actively abetted this extremism".

"America is prepared to stand with you," Trump will say. "But the nations of the Middle East cannot wait for American power to crush this enemy for them."

Trump also announced plans to hold a press conference "in about two weeks" to give an update on how the US is faring in its battle against the Islamic State group.

Some 35 heads of state and government from Muslim-majority countries are in Riyadh for the Arab Islamic American Summit, mainly from Sunni states friendly to Saudi Arabia.

Much of the focus during the summit will be on countering what Gulf states see as the threat from Iran, which opposes Saudi Arabia in a range of regional conflicts from Syria to Yemen.

'Tremendous' first day

Tillerson made several remarks on Saturday taking aim at Iran, including a call for newly re-elected President Hassan Rouhani to dismantle the country's alleged "network of terrorism".

Trump's speech has been touted as a major event -- along the lines of a landmark address to the Islamic world by Obama in Cairo in 2009.

It will be especially sensitive given tensions sparked by the Trump administration's attempted travel ban targeting several Muslim-majority nations and his previous remarks on Islam.

In December 2015, Trump told a campaign rally he was calling for a "total shutdown" of Muslims entering the United States "until our country's representatives can figure out what the hell is going on".

His words shocked many Americans, with Trump detractors noting that the US Constitution prohibits religious discrimination.

"I think Islam hates us. There is a tremendous hatred there. We have to get to the bottom of it," Trump said in a March 2016 interview with CNN.

Still, Trump has been welcomed warmly in Saudi Arabia, where he and first lady Melania Trump were given an extravagant reception by King Salman and the rest of the Saudi royal family.

The trade deals announced on Saturday were said to be worth in excess of $380 billion, and Trump proudly declared the first day of his visit "tremendous".

On Sunday he began a series of meetings with other Arab leaders, including Egyptian President Abdel Fattah al-Sisi, Qatar's Emir Sheikh Tamim bin Hamad Al-Thani and Bahrain's King Hamad.

Warm talks with 'friend' Sisi

The meeting with Sisi -- an avowed fan of the president -- was especially warm and Trump said he would "absolutely" be putting Egypt on his list of countries to visit "very soon".

Trump referred to Sisi as "my friend" and Sisi said the US president was a "unique personality" and "capable of doing the impossible", to which Trump responded: "I agree!"

Trump even complimented Sisi on his footwear, saying: "Love your shoes. Boy, those shoes. Man..."

Sisi has faced harsh criticism of his human rights record since he led the military overthrow of Islamist predecessor Mohamed Morsi in 2013.

Trump, who travels on Monday to Israel and the Palestinian territories before visiting the Vatican, Brussels and Italy for NATO and G7 meetings, is taking his first steps on the world stage as he faces increasing scandal at home.

The last week has seen a string of major developments in Trump's domestic woes, including the announcement that James Comey, the former FBI chief fired by Trump, has agreed to testify publicly about Russian interference in the US elections.

Reports have also emerged that Trump called Comey "a nut job" and that the FBI has identified a senior White House official as a "significant person of interest" in its probe of Russian meddling.