A criminal case under the article "espionage" has been initiated against an American citizen, the press service of the Russian Federal Security Service (FSB) said in a statement.

MOSCOW (Sputnik) — Russian Federal Security Service (FSB) officers detained US citizen Paul Whelan in the Russian capital during a spy action, the FSB's press service said on Monday.

"On December 28, a US citizen Paul Whelan was detained by officers from the Russian Federal Security Service during a spy action in Moscow", the press office said.

The Russian Foreign Ministry has said in a statement that the US Embassy had been notified about the detention of its citizen in accordance with a consular convention.

"All the information that currently can be provided regarding the detention of US citizen Paul Nicholas Whelan is contained in the FSB statements… For our part, we can add that the US Embassy in Moscow was informed in a timely manner of the detention in accordance with the bilateral consular convention," the ministry said.

An investigation is ongoing, it added. The Russian service has not shared any other details on the matter.

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The article, according to which a criminal case was initiated, provides for punishment in the form of imprisonment for a term of 10 to 20 years.

Earlier in December, a Norwegian citizen was detained for similar charges of espionage. The court hearing on the case of Frode Berg is set for February 2019.