Are ISPs obliged to keep such logs in any country out there? I work for one in Russia (quite unhealthy country for Internet those days), and AFAIK we're only s

Are ISPs obliged to keep such logs in any country out there? I work for one in Russia (quite unhealthy country for Internet those days), and AFAIK we're only supposed to keep accounting records (i.e. times, assigned IP addresses etc.)