The defense of Gordon Black, a U.S. soldier being held in the Russian city of Vladivostok on theft charges, appealed his detention, Russia's RIA news agency reported on Monday,

"An appeal was received from the defense," RIA cited a spokesperson for the Pervomaisky District Court in Vladivostok as saying.

Black, who the Pentagon said traveled to Russia without authorisation, was detained in early May until July 2.