MOSCOW (AP) — Russia's Federal Security Service said Thursday it has initiated an espionage case against a U.S. citizen, but did not name the person or specify whether they were in custody.

In a brief statement, the FSB service said the American is “suspected of collecting intelligence information on biological topics directed against the security of the Russian Federation.”

“We are aware of these unconfirmed reports of an investigation regarding a U.S. citizen in Russia," State Department deputy spokesperson Vedant Patel said.

“Generally, the Russian Federation does not abide by its obligations to provide timely notification of the detention of U.S. citizens in Russia," Patel said. "Russian authorities also don’t regularly inform the embassy of the trials, sentencing or movement of U.S. citizens. We’re looking into this matter and will continue to monitor it.”

The charge carries a potential prison term of 10-20 years.

Paul Whelan, a Michigan corporate security executive, has been jailed in Russia for four years on espionage charges that his family and the United States government have said are baseless.