A senior official on Trump's transition team says the US president-elect is close to naming the chief executive of Exxon Mobil as the country's next secretary of state.

Speaking on the condition of anonymity, the official, however, cautioned that no formal offer had been made.

64-year-old Rex Tillerson is one of the five candidates being considered for the position, including 2012 Republican presidential nominee Mitt Romney.

Tillerson has no political experience but oversees the operations of the oil and gas giant in more than 50 countries. He is also known to have close relations with the Kremlin.

In 2013, Russian President Vladimir Putin awarded Tillerson with the Order of Friendship, one of the country's highest civilian honors. Tillerson openly opposes US sanctions against Russia for its seizure of Crimea.