On Friday, a Kiev court authorized their arrest until July 19.
"The Russian side called to provide the Russian Embassy access to E. V. Yerofeyev and A. A. Aleksandrov as soon as possible," the ministry said in a statement.
According to the ministry, Kiev is politicizing the Russian nationals' detention, misusing mass media for this purpose.
The Russian Foreign Ministry on Monday summoned Ukraine's envoy to Moscow Ruslan Nimchinsky over the issue.
Both Russian nationals are facing terrorism charges in Ukraine. According to Ukrainian Security Service spokesman Vitaly Naida, Alexandrov and Yerofeyev may receive prison terms of at least 15 years.
The Russian Defense Ministry has dismissed allegations that the nationals were active-duty servicemen of the Russian Armed Forces, demanding their immediate release.