A Ukrainian journalist is being held in custody in Russia on espionage charges.

Federal Security Service (FSB) officials said on October 3 that Roman Sushchenko was detained in Moscow on September 30.

The FSB claimed Sushchenko is a colonel with Ukrainian military intelligence who has been collecting classified data about Russia's Armed Forces and National Guard.

Meanwhile, Moscow’s Lefortovo district court announced it had ordered Sushchenko be held in pretrial detention for two months.

The reporter's employer, Ukrinform, said Sushchenko was in Moscow on vacation.

The news agency said the accusations against its Paris-based correspondent "can only be described as...yet another flagrant and unlawful [Russian] act against Ukrainian nationals."

Sushchenko's lawyer, Mark Feigin, said his client had no links to any spy agency.

Ukraine's Foreign Ministry demanded Sushchenko’s "immediate release and unhampered return home," and called on Russia to respect the Ukrainian citizen's rights.

Based on reporting by Ukrinform, AP, UNIAN, RIA Novosti, and Interfax