Russia's Olympic Committee (ROC) has banned four athletes for doping, as the country struggles to overturn a suspension on its track and field team that could see it miss the Rio Olympics. 

The Olympic Committee said Irina Maracheva, an 800-metres medalist at the 2012 European championships, had been banned for two years, along with race walker Anna Lukyanova, for doping violations based on documents handed over by the International Association of Athletics Federations (IAAF).

Officials have also confirmed a four-year ban for the runners Yelena Nikulina and Maria Nikolayeva, the Olympic Committee said in a statement dated Sunday.

No more details of the reasons for the bans were given.