Hunter Biden, the son of US Vice-President Joe Biden, has been appointed to the board of directors of Burisma Holdings, Ukraine's largest private gas producer, according to Russia Today.

On Tuesday, the White House brushed aside questions about the ethical issues surrounding his appointment to the post at a time when the administration is promoting energy diversity in Ukraine.

Natural gas has been a central issue in recent tensions between Russia and Ukraine. Kiev depends on Moscow for most of its natural gas and has accused Russia of hiking natural gas prices as punishment for moving closer to the European Union.

Speaking about his new position, Hunter Biden said he would advise on "transparency, corporate governance and responsibility, international expansion and other priorities" in order to "contribute to the economy and benefit the people of Ukraine", according to Russia Today.

The decision immediately sparked speculation over whether the US government had a role in Hunter Biden's promotion, as his father has frequently spoken about the need to increase Ukraine's energy independence.

"Hunter Biden and other members of the Biden family are obviously private citizens, and where they work does not reflect an endorsement by the administration or by the vice-president or president," White House press secretary Jay Carney said.

Reuters-China Daily