For additional protection against unauthorized domain transfer, the current Registrar uses special services. You may check, whether this service is enabled for your domain, using Whois-service:
If Registrar change is impossible, to transfer your domain to RU-CENTER you should contact the current Registrar or Registrar's partner, through which you registered your domain. The name of the domain Registrar is given in the "Registrar" field of Whois-service.