"The investigative department of the FSB of Russia against a U.S. citizen opened a criminal case under article 276 of the Criminal Code of the Russian Federation (Espionage)".
MOSCOW-An American citizen has been arrested in Moscow on suspicion of espionage, Russia's domestic security service, the FSB, said on Monday.
Russian President Vladimir Putin spoke out about the case on December 20, saying he didn't understand why Butina was detained and that he would support her.
The TASS report said Whelan could face between 10 to 20 years in prison if found guilty but disclosed no further details.
A criminal investigation into espionage has been launched against the United States citizen. It said it was pushing for consular access to the detained American. "We have requested this access and expect Russian authorities to provide it".
There was no immediate comment from the White House or U.S. State Department.
Earlier this month, Russian gun rights activist Maria Butina pleaded guilty to conspiring with a senior Russian official to infiltrate USA conservatives.
American authorities detained and charged Russian national Maria Butina with spying earlier this year.
Spy scandals have also rocked diplomatic relations recently in other parts of the world.