US President Donald Trump is expected to underline the need to confront extremism in Islam when he makes a speech in Saudi Arabia later on Sunday.

A leaked version of his speech says the fight against extremism "is not a battle between different faiths" but "a battle between good and evil".

Trump, who is on his first official trip abroad, will deliver the speech at a summit of regional leaders.

His harsh campaign rhetoric on Muslims stirred concern in the Islamic world.

The excerpts suggest a softer tone with Trump attempting to bolster support for the fight against Islamic State terrorists.