unofficially
US /ˌʌn.əˈfɪʃ.əl.i/
UK /ˌʌn.əˈfɪʃ.əl.i/

1.
without official authorization or approval; not formally acknowledged.
:
•
He was unofficially appointed to the position.
•
The news spread unofficially through the office.
without official authorization or approval; not formally acknowledged.