Trump picks ExxonMobil chief Rex Tillerson as top diplomat

Tillerson's nomination comes just days after the CIA accused Russia of interfering with the US election in favour of Trump, in a development which could complicate the CEO's confirmation.

"Rex knows how to manage a global enterprise, which is crucial to running a successful State Department, and his relationships with leaders all over the world are second to none," Trump said in a statement.

As ExxonMobil's president and chief executive, the 64-year-old Texan oversees the company's business activities in more than 50 countries.

He has opposed sanctions on Russia and in 2013 was awarded Russia's Order of Friendship by President Vladimir Putin following several years of Exxon projects in the country.

"I can think of no one more prepared, and no one more dedicated, to serve as Secretary of State at this critical time in our history," Trump said.

US media have reported for days on secret CIA findings that Moscow sought to bolster Trump's election bid against Democratic former secretary of state Hillary Clinton by releasing hacked Democratic Party documents.

Tillerson - who has no formal foreign policy background - is sure to face sharp questions in Senate confirmation hearings.

Leading senators on Monday threw their backing behind a congressional investigation into US intelligence assessments on Russia election interference, putting top Republicans on a collision course with the incoming president.