unofficially
adverb /ˌʌnəˈfɪʃəli/
  /ˌʌnəˈfɪʃəli/
- without having permission or approval from somebody in authority- Costs were unofficially estimated at about $6 000.
- He had already been doing the job unofficially, and now he would be paid for it.
 
- without being part of somebody's official business- US officials have visited the country unofficially in the past.
 opposite officially