U.S. national Paul Whelan, who was detained last week in Moscow on suspicion of espionage, also has British citizenship, Russian Foreign Ministry spokesperson Maria Zakharova said Friday.

Paul Whelan, a U.S. citizen detained in Russia for suspected spying, appears in a photo provided by the Whelan family on January 1, 2019. [File photo: Xinhua]

Britain has asked for a consular visit to Whelan and both sides are working on it, Zakharova confirmed, after the British embassy in Russia said it has made such a request.

U.S. Ambassador to Russia Jon Huntsman has visited Whelan in a detention facility and expressed support for him.

The Russian Federal Security Service said on Dec. 31 that it detained Whelan in Moscow for spying three days earlier and has initiated a criminal case against him.

According to media reports, the 48-year-old Whelan was a U.S. Marine and his family said he traveled to Moscow only to attend a friend's wedding.

The incident came after Russian citizen Maria Butina pleaded guilty in a Washington court on Dec. 13 to one conspiracy charge, admitting that she acted as an unregistered foreign agent to advance Moscow's interests.

Russian President Vladimir Putin said Butina has no ties to Russian intelligence services and the whole case against her was unfounded.