U.S. Senate minority leader Chuck Schumer called on the FBI and the Federal Trade Commission to conduct a national security and privacy investigation into FaceApp, a face-editing photo app developed in Russia, in a letter sent on Wednesday.

The viral smartphone application, which has seen a new surge of popularity due to a filter that ages photos of users' faces, requires "full and irrevocable access to their personal photos and data," which could pose "national security and privacy risks for millions of U.S. citizens," Schumer said in his letter to FBI Director Christopher Wray and FTC Chairman Joe Simons.

The Democratic National Committee also sent out an alert to the party's 2020 presidential candidates on Wednesday warning them against using the app, pointing to its Russian provenance. In the email, first reported by CNN, DNC security chief Bob Lord also urged Democratic presidential campaigns to delete the app immediately if they or their staff had already used it.

There is no evidence that FaceApp provides user data to the Russian government.

Democrats have invested heavily in bolstering party cyber defenses after U.S. intelligence agencies determined that Russia used hacking as part of an effort to boost support for President Donald Trump’s 2016 election campaign. Russia has repeatedly denied those claims.