There's more 'accusations' than that though...

"Because, shortly before his graduation, his bosses learned that Putin was a pedophile. So say some people who knew Putin as a student at the Institute....Many years later, when Putin became the FSB director and was preparing for presidency, he began to seek and destroy any compromising materials collected against him by the secret services over earlier years. It was not difficult, provided he himself was the FSB director. Among other things, Putin found videotapes in the FSB Internal Security Directorate, which showed him making sex with some underage boys." --Litvinenko

Whether or not he's accurate about this appears to remain speculative...