The World Anti-Doping Agency has opened an investigation into allegations of Russian doping at the 2014 Winter Olympics in Sochi.

A programme on American network CBS claimed several Russian athletes, including gold medallists, used performance enhancing drugs at the Games.

WADA president Sir Craig Reedie says his organisation will look into the allegations immediately.

"The claims made in the program offer real cause for concern, as they contain new allegations regarding attempts to subvert the anti-doping process at the Sochi Games," he said, adding that they will "probe these new allegations immediately".

Read the full WADA statement here.