Moscow accused Washington of kidnapping Roman Seleznev who was detained at an airport in the Maldives and accused of hacking into U.S. retailers' computer systems to steal credit card data.
The arrest of the 30-year-old son of a deputy in Russia's lower house of parliament has increased tensions between the two countries, already at their worst since the end of the Cold War over the Ukraine crisis.
"From our side, we stressed the unacceptability of such actions which are a flagrant violation of the legitimate rights and interests of the Russian citizen, who was in fact kidnapped from the territory of a third country," the Foreign Ministry said in a statement.
It issued a demarche - a formal diplomatic statement of concern - to a representative of the U.S. embassy.
"We again demanded the immediate release of Roman Seleznev, providing him with adequate medical care and in general respecting his legal rights and interests," the ministry said.
The U.S. State Department has dismissed Moscow's accusations of kidnapping, saying Seleznev was indicted in the state of Washington in March 2011 on charges including bank fraud, causing damage to a protected computer, obtaining information from a protected computer and aggravated identity theft.
© Thomson Reuters 2014