Donald Trump has reportedly been advised to hire a lawyer amid allegations about his presidential campaign's ties to Russia, as the spectre of impeachment threatens to overshadow his first overseas trip as President.

The New York Times claims President Trump has been urged to seek independent legal advice following allegations he asked FBI director James Comey to drop an investigation into national security adviser Michael Flynn, a crisis engulfing the presidency.

Visiting Riyadh, Trump will hope to put domestic troubles behind him, with the focus on strengthening an already comfortable relationship between the Saudis and America.

Saudi Arabia is looking to assert its regional leadership against Iran by hosting a summit between visiting US President Donald Trump and Muslim leaders from around the world. The president is expected to tell Muslim leaders of his "hopes for a peaceful vision of Islam" as he seeks support for the war against radical Islamists.