WASHINGTON (AP) — The top Senate Democrat is calling on the FBI to review a Russian company's trendy smartphone app that transforms faces from photos into younger and older images of the person, according to a letter obtained by The Associated Press.

Senator Chuck Schumer says in the letter Wednesday to the FBI and Federal Trade Commission that he's concerned FaceApp could pose "national security and privacy risks for millions of U.S. citizens."

The New York Democrat is asking the agencies to assess the situation. He says it would be "deeply troubling" if sensitive personal information was provided "to a hostile foreign power actively engaged in cyber hostilities against the United States."

Many popular apps collect user data, but concerns have circulated about FaceApp, which is developed in Russia by Wireless Lab.