ExxonMobil Chairman and CEO Rex Tillerson speaks during the IHS CERAWeek 2015 energy conference in Houston, Texas April 21, 2015. [Photo/Agencies]

WASHINGTON -- US President-elect Trump is expected to nominate Exxon Mobil Chief Executive Rex Tillerson as his secretary of state, NBC News reported on Saturday, quoting two sources close to the transition process.

However, NBC reported that the unnamed sources cautioned that nothing is final till Trump officially announces the pick probably next week.

Tillerson, 64, is the Texas-based oil company's CEO since 2006 and had moved ahead of other candidates for the position of the country's top diplomat after former New York Mayor Rudy Giuliani, once a favorite to be the next U.S. secretary of state, dropped out of the competition on Friday.

Meanwhile, NBC quoted one source as saying that former U.S. Ambassador to the United Nations John Bolton would be deputy secretary of state "for day-to-day management of the department."

Like Trump, Tillerson has no government experience and so far little is known of Tillerson's views about foreign affairs.

The Wall Street Journal quoted sources as saying that Tillerson's initial emergence as a candidate for the country's top diplomat surprised senior Exxon officials, including Tillerson himself.

But in Tillerson, a seasoned business executive, some Trump advisers saw a "mold-breaking pick who would bring an executive's experience to the diplomatic role," the Journal reported.

As Exxon's CEO, Tillerson, set to retire from the company in 2017, oversees business operations in over 50 countries and has known Russian President Vladimir Putin since 1990s when they first met.

Tillerson was awarded Russia's Order of Friendship in 2013, a state decoration to reward foreign nationals whose work is aimed at the betterment of relations with Russia.

Tillerson joined Exxon in 1975 and has spent his entire career at the company.