MOSCOW — Russia’s top investigative agency said Friday it has proof of opposition supporters attending training abroad as part of foreign-backed plans to overthrow the government.

Vladimir Markin, spokesman for the Investigative Committee, said it had evidence confirming earlier charges that leftist activists Sergey Udaltsov, Leonid Razvozzhayev, and Konstantin Lebedev met with foreign officials to plot mass riots, inspired by the ‘‘color revolutions’’ that ousted authoritarian leaders in several former Soviet nations and rattled the Kremlin.