The Russian Embassy in the United States has requested from US authorities urgent medical assistance for Konstantin Yaroshenko, in connection with a sharp deterioration in his health.
For the time spent in the US prison, the health of the Russian pilot has seriously suffered, it added.
Yaroshenko has also requested that he be transferred to Russia to serve out his remaining prison term three times in line with the international Convention on the Transfer of Sentenced Persons, but his applications have been rejected.
Yaroshenko was captured in Liberia in 2010 and brought into the United States where he was sentenced to 20 years in prison the following year on charges of conspiring to import drugs. The pilot has denied the charges.